• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.5
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• pp.115-121
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• 2009

In this paper, we propose an algorithm that reduces channel change delay time in the P2P based IPTV system. Channel change delay time is considered to be one of the most important performance measures in IPTV system. Proposed algorithm presents a method to reduce the channel change delay time effectively. The algorithm eliminates the first channel change delay time and reduces delay time on a continuous channel surfing. We will show the mathematical models to evaluate the performance of proposed scheme with respect to the channel change delay time.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.6
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• pp.577-583
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• 2011

Radar performance test is one of the major steps for radar system design. However, it is restricted by time and cost when radar performance tests are performed with opportunity targets. So various simulated target generators are developed and used to evaluate radar performance. To simulate the target's range, most of simulated target generators are developed with optical line or DRFM(Digital RF Memory) technique but there are many restrictions such as limit of range imitation and test scenario because of their original usage. In this paper, DDL(Digital Delay Line) module for development of simulated target generator is designed with precise range simulation and easily embodiment feature. And pulse recognition and delay gap detection technique are used to simulate the time delay without distortions. Developed DDL module performances are verified through their performance tests and test results are described in this paper.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.2
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• pp.191-198
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• 2013

Geo-pointing is a function that maintains LOS(Line of Sight) to a stationary ground target by controlling azimuth and elevation angles of a EOS(Electro-Optical System) which are calculated from aircraft navigation data and target coordinates. In design and implementation of the geo-pointing, a transmission time delay between GPS/INS and EOS is a major degradation factor of the geo-pointing performance when the aircraft is rapidly maneuvered especially. In this paper, a kalman filter is designed to compensate the transmission time delay of aircraft navigation data. Simulation and test results show that the geo-pointing performance is enhanced by the proposed compensation technique.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.7
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• pp.618-624
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• 2004

This paper presents a delay dependent fuzzy H_\infty$ filter design method for delayed fuzzy dynamic systems. Using delay-dependent Lyapunov function, the global exponential stability and H_\infty$ performance problem are discussed. A sufficient condition for the existence of fuzzy filter is presented in terms of linear matrix inequalities(LMIs). The filter design utilize the concept of parallel distributed compensation. And the filter gains can also be directly obtained from the LMI solutions. A simulation example is given to illustrate the design procedures and performance of the proposed methods.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.470-473
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• 2002

Most networks for automation are tuned to an expected traffic at their design stage. During their actual operations, however, the networks experience considerable changes in traffic from time to time. These traffic changes caused by common events like machine failure and production schedule change may adversely affect the network performance and, in turn, the performance of the connected devices. This paper presents communication delay model for Profibus token passing protocol, and introduces TTR selection methods to maintain a uniform level of network performance at all stations under changing network traffic.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.1-3
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• 2006

This paper deals with a novel utilization method of the predicted current in the high performance PI current controller with a control time delay. The inevitable error of the predicted current in the linear servo drive using a permanent magnet linear synchronous motor is analyzed and a modified cross-coupling decoupling synchronous frame PI current controller is proposed in order to improve the current control response under the control time delay. Simulation and experimental results show that the proposed current controller has an improved current control performance under both the electrical uncertainties of a servo drive system and the control time delay.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2089-2092
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• 2002

The PID controller have the simple structure and show the comparatively good control performance. Crystal Grower(FF-CZ150) melt polycrystalline silicon at the temperature of about 1450$^{\circ}C$, then grow it into a single crystalline ingot. The automatic diameter control system of the Crystal Grower has a good performance with only PD control. But it contain the integrator in the plant which has a long time delay. In this paper, we show the secondary approximate model and applies time delay controller which has good performance for the plant with long time delay. It will be able to improve the response characteristic against a standard input and a load disturbance.

• ETRI Journal
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• v.18 no.3
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• pp.127-145
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• 1996

A new analytic framework based on a linear algebra approach is proposed for examining the performance of a direct sequence spread spectrum (DS/SS) slotted ALOHA wireless communication network systems with delay capture. The discrete-time Markov chain model has been introduced to account for the effect of randomized time of arrival (TOA) at the central receiver and determine the evolution of the finite population network performance in a single-hop environment. The proposed linear algebra approach applied to the given Markov problem requires only computing the eigenvector ${\prod}$ of the state transition matrix and then normalizing it to have the sum of its entries equal to 1. MATLAB computation results show that systems employing discrete TOA randomization and delay capture significantly improves throughput-delay performance and the employed analysis approach is quite easily and staightforwardly applicable to the current analysis problem.

• IEMEK Journal of Embedded Systems and Applications
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• v.6 no.3
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• pp.149-156
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• 2011

Transmission delay and packet loss induced by a communication network can degrade the control performance and, even make the system unstable. This paper presents a method for compensating transmission delay and packet loss in a networked control system for unmanned underwater vehicle. The proposed method is based on Lagrange interpolation in order to satisfy the requirements of simplicity and model-independency. In this work, the lost/delayed data are estimated in real time by only using the past data without requiring any mathematical model of the controlled system. Consequently, the proposed method can be implemented independent of the controlled system, and also it can achieve fast and accurate compensation performance. The performance of the proposed technique is evaluated by numerical simulations with an unmanned underwater vehicle.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.6
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• pp.263-268
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• 2010

As the demand of high quality service in next generation wireless communication systems, a high performance of data transmission requires an increase of spectrum efficiency and an improvement of error performance in wireless communication systems. In this paper, we propose a multi-user multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) system with cyclic delay diversity and block diagonalization procoding method to improve bit error rate (BER) performance with wireless local area network (WLAN) channel model C and D for 802.11n WLAN system. The results of mathlab simulation show the improvement of BER performance in 802.11n wireless indoor channel environment.