• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.58-58
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• 2000

As many sensors and actuators are used in various automated systems, the application of network system to real-time distributed control is gaining acceptance in many industries. In order to take advantages of the network technique. however, network implementation should be carefully designed to satisfy real-time constraints and to consider network delays. This paper presents the implementation of feedback control system in Profibus-DP. Profibus-DP is a type of fieldbus protocols that are specifically designed to interconnect simple devices with fast I/O data exchange. As feedback control in profibus-DP is implemented, Network delays is found with influence of system performance. We analyze network delays in Profibus-DP into 3 reasons - dead time in Profibus interface, protocol delay, delay by asynchronization. In order to compensate the network delays, we introduce control algorithms with time delay concept. The results show that network delay can be compensated.

• 한국시뮬레이션학회논문지
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• 제13권2호
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• pp.65-73
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• 2004

The capability to provide the network service must survive even if a significant network system element is disrupted. To sustain the network service under the system failure, network survivability mechanisms minimizing the impact of failures are needed. Also, since the mobile network has its unique characteristic, the survivability scheme for the vulnerability of the mobile network is required. This paper proposes a survivability scheme to support the reliable service of the wireless access point level (BS-base station system). By the survivability scheme, the mobile network can use an overlap BS of the cellular network architecture after a BS system failure. We analyze the performance of the proposed scheme using Markov model. Also, a computer simulation is used for the scheme analysis. The proposed scheme shows that the service of the mobile network can be provided under the BS system failure.

• 대한전기학회논문지
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• 제43권5호
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• pp.838-847
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• 1994

Although there is an analytical proof of modeling capability of the neural network, the convergency error in nonlinearity modeling is inevitable, since the steepest descent based practical larning algorithms do not guarantee the convergency of modeling error. Therefore, it is difficult to apply the neural network to control system in critical environments under an on-line learning scheme. Although the convergency of modeling error of a neural network is not guatranteed in the practical learning algorithms, the convergency, or boundedness of tracking error of the control system can be achieved if a proper feedback control law is combined with the neural network model to solve the problem of modeling error. In this paper, the neural network is introduced for compensating a system uncertainty to control a nonlinear dynamic system. And for suppressing inevitable modeling error of the neural network, an iterative neural network learning control algorithm is proposed as a virtual on-line realization of the Adaptive Variable Structure Controller. The efficiency of the proposed control scheme is verified from computer simulation on dynamics control of a 2 link robot manipulator.

• Journal of Communications and Networks
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• 제12권1호
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• pp.11-18
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• 2010

Diversity-multiplexing tradeoff (DMT) is an efficient tool to measure the performance of multiple-input and multiple-output (MIMO) systems and cooperative systems. Recently, cooperative multicast system with wireless network coding stretched tremendous interesting due to that it can drastically enhance the throughput of the wireless networks. It is desirable to apply DMT to the performance analysis on the multicast system with wireless network coding. In this paper, DMT is performed at the three proposed wireless network coding protocols, i.e., non-regenerative network coding (NRNC), regenerative complex field network coding (RCNC) and regenerative Galois field network coding (RGNC). The DMT analysis shows that under the same system performance, i.e., the same diversity gain, all the three network coding protocols outperform the traditional transmission scheme without network coding in terms of multiplexing gain. Our DMT analysis also exhibits the trends of the three network coding protocols' performance when multiplexing gain is changing from the lower region to the higher region. Monte-Carlo simulations verify the prediction of DMT.

• 전자공학회논문지A
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• 제30A권12호
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• pp.1-9
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• 1993

In this paper, to realize the network management function in automated manufacturing network Mini-MAP, the network management requirements are analyzed and the network management system is implemented on the basis of this analysis. The implemented management system which has both local management and remote management mechanism is considered as a single domain on the Mini-MAP network. Here, the remote management functions consist of network status, monitoring and remote operations and the local management functions have parameter display and network self testing. The MAP network controller is designed according to the MAP version 3.0 specifications and IEEE 802 standards. the operations of network management system are certified througth the test environments which consists of the implemented network adaptor and softwares for Mini-MAP.

• 대한지리학회지
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• 제44권2호
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• pp.187-205
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• 2009

최근 지리학 및 교통 관련 분야에서는 교통 네크워크의 잠재적 손실이 지리 공간상에서 어떠한 영향을 주는가를 살피는 연구가 중요한 주제로 등장하고 있다. 서울의 지하철망은 대규모의 도심 통행을 지지히는 중요한 기반시설이며, 특히 환승역은 그 기능을 상실할 경우 전체 교통망의 신뢰도에 큰 영향을 줄 수 있는 중요한 교통 입지시설이다. 이 논문은 지하철 환승역의 기능 손실이 지하철망의 신뢰도과 대응력에 어떠한 영향을 주는지를 네트워크의 위상학적인 차원, 전체 지리 공간, 그리고 개별 환승역 차원에서 살펴본다. 시뮬레이션을 통한 분석 결과, 서울 지하철망은 상당히 높은수준의 네트워크 신뢰도를 보였으나 환승역 간에는지리적으로 유의미한 변이가 있음을 확인하였다.

• 한국데이타베이스학회:학술대회논문집
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• 한국데이타베이스학회 1999년도 춘계공동학술대회: 지식경영과 지식공학
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• pp.307-313
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• 1999

This paper reviews and assesses the analogy between the human immune system and network intrusion detection systems. The promising results from a growing number of proposed computer immune models for intrusion detection motivate this work. The paper begins by briefly introducing existing intrusion detection systems (IDS's). A set of general requirements for network-based IDS's and the design goals to satisfy these requirements are identified by a careful examination of the literature. An overview of the human immune system is presented and its salient features that can contribute to the design of competent network-based IDS's are analysed. The analysis shows that the coordinated actions of several sophisticated mechanisms of the human immune system satisfy all the identified design goals. Consequently, the paper concludes that the design of a novel network-based IDS based on the human immune system is promising for future network-based IDS's

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전력기술부문
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• pp.244-246
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• 2008

EMTP-RV is the very powerful program to analyze the dynamic operation of the power system. To use this package in the large complex power system, it is very important to simplify the power system to simple equivalent network. In our study the 100 MVA STATCOM is placed at 345kV "MIGUM" which is the one of the 345kV substations of the Korean Electric Power System that is consist of more than 1000 bus. MIGUM substation is connected with 7 separated transmission lines to main Korean Electric power system. We developed a new method to simplify the network except the substation that we want to analysis. The power system outside the 345kV substation is modeled into the equivalent network. The loop network outside the substation can be modeled to simplified Thevenin equivalent network. The proposed method is applied to IEEE-14 Reliability Test System and the results shows the effectiveness of the method.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2003년도 한국우주과학회보 제12권2호
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• pp.56-56
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• 2003

과학위성 1호의 OBC(On-Board Computer)와 Sybsystem 간, Subsystem간, 또는 위성과 지상국간의 통신이 가능해야한다. 그리고 OBC(On-Board-Computer)나 지상국에서의 위성의 모듈들을 명령(Command)을 통하여 제어할 수 있어야 한다. 또한 모듈들을 원격검침(Telemetry)을 통하여 상태를 확인할 수 있어야 한다. 위에서 언급한 기능을 수행하는 모듈이 바로 Network System이다 과학위성1호에는 총 6개의 Network System이 구현되었다. 각각의 Network System들은 여러 Subsystem들과 연결되어있고, Network System간에 또한 연결되어서 Subsystem간의 통신과 Network System에 연결된 모듈들을 제어하고 상태를 수집한다. 본 연구에서는 과학위성1호 Network System의 구조, 기능, Spec 및 연구 개발 내용을 소개한다.

• 한국정밀공학회지
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• 제15권4호
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• pp.15-26
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• 1998

Full car model is needed for investigating as a entire dynamics of vehicle. In this study, 7DOF of full car model's dynamics is selected. This paper proposes the output feedback controller based on optimal control theory. Input data and output data from the optimal controller are used for neural network system identification of the suspension system. To do system identification, neural network which has robustness against nonlinearities and disturbances is adapted. This study uses back-propagation algorithm to train a multil-layer neural network. After obtaining a neural network model of a suspension system, a neuro-controller is designed. Neuro-controller controls suspension system with off-line learning method and multistep ahead prediction model based on the neural network model and a neuro-controller. The optimal controller and the neuro-controller are designed and then, both performances are compared through. For simulation, sinusoidal and rectangular virtual bumps are selected.