• 천문학논총
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• 제20권1호
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• pp.63-71
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• 2005

e-VLBI was invented to enhance the efficiency of VLBI (Very-Long-Baseline Interferometry) system by transmitting the data via high speed network. Korean VLBI Network (KVN) has a plan to construct e-VLBI system named e-KVN. High speed backbone network and efficient network model are essential to implement successful e-VLBI system. This paper introduces a network model based on PC cluster technology. The present status of high speed backbone network in Korea is overviewed. We suggest that the network link via Korea Advanced Research Network (KOREN) is one of feasible way for e-KVN. We also describe the principles of e-VLBI and protocol for network transmission such as VSI-E (VLBI Standard Interface - Electronic), RTP (Real-Time Transport Protocol) and RTCP (Real-Time Transport Control protocol).

• 한국인터넷방송통신학회논문지
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• 제10권6호
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• pp.225-233
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• 2010

최근, 스마트 그리드, 스마트 홈 네트워크, 유비쿼터스 컴퓨팅 등의 분야에서 필요한 정보를 수집 및 가공하여 실시간 양방향으로 교환하고, 제어 및 감시하는 스마트 정보 모니터링 기술에 대한 연구를 계속 해 왔다. 본 논문에서는 에너지, U-Farm, 차량정보 및 홈 네트워크에 관한 스마트 정보 모니터링 기술의 응용 제품 및 최근 동향들을 알아본다. 특히, 스마트 그리드의 핵심부분인 스마트 미터와 실시간으로 정보를 교환하는 구글 파워미터, 유비쿼터스 농업을 위한 실시간 모니터링 시스템, 차량상태 정보를 위한 실시간 모니터링 시스템, 저전력, 저가격의 ZigBee 기반 스마트 정보 모니터링 기술 응용 및 관련사례에 대하여 기술한다. 마지막으로 스마트그리드 제주 실증단지 구축현황에 대하여 기술한다.

• 한국안전학회지
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• 제21권4호
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• pp.25-32
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• 2006

LonWorks over IP(LonWorks-IP) virtual device network(VDN) is an integrated form of LonWorks device network and IP data network. In especially real-time distributed servo applications on the factory floor, timely response is essential for predictive and preventive maintenance. The time delay in servo control on LonWorks-IP based VDN has highly stochastic nature. LonWorks-IP based VDN induced transmission delay deteriorates the performance and stability of the real-time distributed control system and can't give an effective preventive and predictive maintenance. In order to guarantee the stability and performance of the system, and give an effective preventive and predictive maintenance, LonWorks-IP based VDN induced time-varying uncertain time delay needs to be predicted and compensated. In this paper new Pill control scheme based on Smith predictor, disturbance observer and band pass filter is proposed and tested through computer simulation about position control of DC servo motor. It is shown that how can the proposed control scheme be designed to minimize the effects of uncertain varying time delay and model uncertainties. The validity of the proposed control scheme is compared and demonstrated with the comparison of internal model controllers(IMC) based on Smith predictor with and without disturbance observer.

• Journal of Information Processing Systems
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• 제13권2호
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• pp.348-359
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• 2017

Nowadays most vehicles are equipped with a variety of electronic devices to improve user convenience as well as its performance itself. In order to efficiently interconnect these devices with each other, Controller Area Network (CAN) is commonly used. However, the CAN requires reconfiguration of the entire network when a new device, which is capable of supporting both of transmission and reception of data, is added to the existing network. In addition, since CAN is based on the collision avoidance using address priority, it is difficult that a new node is assigned high priority and eventually it results in transmission delay of the entire network. Therefore, in this paper we propose a new system component, called CAN coordinator, and design a new CAN framework capable of supporting plug and play functionality. Through experiments, we also prove that the proposed framework can improve real-time ability based on plug and play functionality.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1999년도 추계학술대회 논문집 - 한국공작기계학회
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• pp.113-118
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• 1999

This paper presents a new approach to the design of neural control system using digital signal processors in order to improve the precision and robustness. Robotic manipulators have become increasingly important n the field of flexible automation. High speed and high-precision trajectory tracking are indispensable capabilities for their versatile application. The need to meet demanding control requirement in increasingly complex dynamical control systems under significant uncertainties, leads toward design of intelligent manipulation robots. The TMS320C31 is used in implementing real time neural control to provide an enhanced motion control for robotic manipulators. In this control scheme, the networks introduced are neural nets with dynamic neurons, whose dynamics are distributed over all the network nodes. The nets are trained by the distributed dynamic back propagation algorithm. The proposed neural network control scheme is simple in structure, fast in computation, and suitable for implementation of real-time control. Performance of the neural controller is illustrated by simulation and experimental results for a SCARA robot.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 D
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• pp.2531-2533
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• 2002

In this paper, we evaluate feasibility of an object-oriented method in a distributed real-time control environment through the prediction of delay expected. We adopt CAN as the distributed network and the application layer of the CAN is composed of client/server communication model of COM and surroundings for the support of real-time capability of the COM. Mathematical models formalizing delays which are predicted to invoke in the COM architecture are proposed. Sensors and actuators which are widely used in distributed network-based systems are represented by COM objects in this paper. It is expected that the mathematical models can be used to protect distributed network-based systems from violation of real-time features by the COM.

• 한국정보과학회논문지:데이타베이스
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• 제37권6호
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• pp.324-332
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• 2010

실시간 임베디드 센서 네트워크 시스템에서의 이벤트 감지는 대부분 현실세계에서 수집된 센서 데이터들의 조합에 기반한다. 이에 최근에 이루어진 연구들에선 센서 데이터들을 수집, 집계하는 낮은 수준의 다양한 메커니즘들을 제안하였다. 그러나 실시간에서 연속적으로 발생하는 복잡한 이벤트들의 감지와 다양한 종류의 센서들로부터 입력되는 실시간 데이터의 처리를 위한 시스템에 대한 솔루션은 보다 많은 연구를 필요로 한다. 즉, 경량의 데이터 혼합이 가능하고 많은 컴퓨팅 자원을 필요로 하지 않는 실시간 이벤트 감지 기법이 필요하다. 이벤트 감지 프레임워크는 실시간 모니터링과 센서 데이터의 도착으로 일어나는 데이터 융합 메커니즘을 통하여 적시성과 임베디드 센서 네트워크의 자원 요구량을 감소시킬 수 있는 잠재력을 지니고 있다. 또한 임베디드 센서 네트워크 시스템이 신뢰성을 지닐 수 있도록 하기 위한 기반 기술인 프라이버시를 보장할 수 있는 익명화 기술을 설명한다.

• 대한기계학회논문집A
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• 제28권11호
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• pp.1637-1645
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• 2004

In remote control of telerobotics equipment, the real-time visual feedback is necessary in order to facilitate real-time control. Because of the network congestion and the associated delays, the real-time image feedback is generally difficult in the public networks like internet. If the remote user is not able to receive the image feedback within a certain time, the work performance may tend to decrease, and it makes difficulties to control of the telerobotics equipment. In this paper, we propose an improved visual feedback scheme over the internet for telerobotics system. The size of a remote site image and its quality are adjusted for efficient transmission. The constructed system has a better real-time update characteristics, and shows a potential for the real-time visual control of the telerobotics system.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.2015-2020
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• 2008

Real-time communication network is important for KTX high speed train system because small problem can make a huge accident. Communication network for KTX high speed train system consists of IEEE 802.4 token bus network and FM0 encoding. The network device is developed by using MC68824 TBC, MC68185 TPM and MC68020 MPU. The network device make available to analysis of the network protocol among vehicles for Kyung-Boo high-speed train system.

• International journal of advanced smart convergence
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• 제5권1호
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• pp.34-46
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• 2016

Networked Control System (NCS) has evolved in the past decade through the advances in communication technology. The problems involved in NCS are broadly classified into two categories namely network issues due to network and control performance due to system network. The network problems are related to bandwidth allocation, scheduling and network security, and the control problems deal with stability analysis and delay compensation. Various delays with variable length occur due to sharing a common network medium. Though most delays are very less and mostly neglected, the network induced delay is significant. It occurs when sensors, actuators, and controllers exchange data packet across the communication network. Networked induced delay arises from sensor to controller and controller to actuator. This paper presents an adaptive delay compensation process for efficient control. Though Smith predictor has been commonly used as dead time compensators, it is not adaptive to match with the stochastic behavior of network characteristics. Time delay adaptive compensation gives an effective control to solve dead time, and creates a virtual environment using the plant model and computed delay which is used to compensate the effect of delay. This approach is simulated using TrueTime simulator that is a Matlab Simulink based simulator facilitates co-simulation of controller task execution in real-time kernels, network transmissions and continuous plant dynamics for NCS. The simulation result is analyzed, and it is confirmed that this control provides good performance.