• 한국통신학회논문지
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• 제23권4호
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• pp.940-949
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• 1998

본 논문에서는 고속 무선채널올 통해 실시간 동영상 정보를 전송할 때 이동 수신측에서 적응적 버퍼제어방법을 사용함으로서 셀 경계에서 핸드오버 등으로 인해 발생되는 지연 스파이크(delay spike)에 대해 효과적으로 대처할 수 있는 방안을 제안한다. 제안한 방법을 확인하기 위해 무선채널의 랜덤오류와 버스트 오류 및 핸드오버 등에 의한 패킷 전송지연 특성을 모델링하고, 본 논문에서 제안한 방식과 기존에 제안된 방식을 패킷 전송지연 모델에 적용하여 지연 및 지연 스파이크에 의한 수선버퍼의 적응도를 비교, 평가하였다. 또한 H.263방식으로 압축한 동영상 데이터를 제안한 알고리즘에 적용해 봄으로서 버퍼지연과 버퍼넘침 발생 등이 기존-의 방식에 비해 감소함을 확인하였다.

• Journal of electromagnetic engineering and science
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• 제12권2호
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• pp.166-170
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• 2012

This paper presents a tunable composite right/left-handed (CRLH) delay line for a delay line discriminator that linearizes modulated frequency sweep in a frequency modulated continuous wave (FMCW) radar transmitter. The tunable delay line consists of 8 cascaded unit cells with series varactor diodes and shunt inductors. The reverse bias voltage of the varactor diode controlled the group delay through its junction capacitance. The measured results demonstrate a group delay of 8.12 ns and an insertion loss of 4.5 dB at 250 MHz, while a control voltage can be used to adjust the group delay by approximately 15 ns. A group delay per unit cell of approximately 1 ns was obtained, which is very large when compared with previously published results. This group delay can be used effectively in FMCW radar transmitters.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.903-908
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• 2006

As environmental vibration requirements on precision equipment become more stringent. use of pneumatic isolators has become more popular and their performance is subsequently required to be further improved. Dynamic performance of passive pneumatic isolators is related to various design parameters in a complicated manner and, hence, is very limited especially in low frequency range by volume of chambers. In this study, an active control technique, so called time delay control which is considered to be adequate for a low frequency or nonlinear system, is applied to a single chamber pneumatic isolator. The procedure of applying the time delay control law to the pneumatic isolator is presented and its effectiveness in enhancement of transmissibility performance is shown based on simulation and experiment. Comparison between passive and active pneumatic isolators is also presented.

• 한국경영과학회지
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• 제24권2호
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• pp.95-108
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• 1999

The CDMA mobile system consists of several subsystems and each subsystem has many processing elements that handle voice messages and control messages for performing CDMA call processing functions through CDMA Interconnection Network(CIN). For assuring a high throughput and a short delay in the CIN, an efficient medium access control protocol should be provided. In this paper, we propose a new access control protocol of CIN for providing real time communications in CDMA mobile system. Also, we evaluate the delay performance of the proposed access control protocol and compare it with that of the existing access control protocol. Through a set of numerical examples, we show that our proposed protocol provides a better delay performance than the existing protocol.

• International Journal of Control, Automation, and Systems
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• 제5권5호
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• pp.492-500
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• 2007

This paper focuses on the problem of guaranteed cost control for a class of uncertain linear delay systems with actuator failures. When actuators suffer "serious failure" the never failed actuators can not stabilize the system, based on switching strategy of average dwell time method, under the condition that activation time ratio between the system without actuator failure and the system with actuator failures is not less than a specified constant, a sufficient condition for exponential stability and weighted guaranteed cost performance are developed in terms of linear matrix inequalities (LMIs). Finally, as an example, a river pollution control problem illustrates the effectiveness of the proposed approach.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.837-843
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• 2006

As environmental vibration requirements on precision equipment become more stringent, use of pneumatic isolators has become more popular and their performance is subsequently required to be further improved. Performance of passive pneumatic isolators is related to various design parameters in a complicated manner and, hence, is very limited especially in low frequency range by chamber volume. In this study, transmissibility behavior of the pneumatic isolators depending on frequency and dynamic amplitude are presented. Then, an active control technique, time delay control, which is adequate for a low frequency nonlinear system, is applied. A procedure of applying the time delay control law to a pneumatic isolator is presented and it's effectiveness in the transmissibility performance is shown. Comparison between passive and active pneumatic isolators is made based on simulation.

• 제어로봇시스템학회논문지
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• 제6권9호
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• pp.752-757
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• 2000

This paper considers a decentralized control problem of dicrete LTI systems which have time delay between interconnections. This paper provides sufficient conditions for the decentralized controller to exist as a H$\infty$ disturbance attenuation ${\gamma}$ of a scaled system and shows that the controller can be designed by using the discrete standard $H_{\infty}$ control theory.

• 한국멀티미디어학회논문지
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• 제10권8호
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• pp.1039-1051
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• 2007

본 논문은 비디오통신 시스템에서 초저지연을 달성하면서 립싱크 제어하는 방법을 제안한다. 초저지연 비디오 통신에서 핵심적인 기술은 종단간 지연시간을 줄이는 기술과 립싱크 제어 기술이다. 특히 서비스관점에서 립싱크 제어 기술이 중요한 요인으로 작용하고 있다. 오디오와 비디오의 데이터를 RTP/RTCP 기반으로 패킷을 구성하여 전송하고, 이 패킷을 이용하여 오디오와 비디오의 재생시간을 계산한 후 립싱크 제어를 한다. 본 논문에서는 오디오 데이터가 일정한 간격으로 재생되도록 하고, 오디오가 재생되는 시점에서 가장 근접한 재생시간을 가진 비디오 데이터를 찾아서 재생하는 방법으로 오디오와 비디오간의 립싱크 제어하는 방법을 제안한다. 그리고 종단간 지연시간이 100 ms이하인 초저지연 비디오 통신을 하기 위해서는 송신단의 인코딩 버퍼 제거하여 지연시간을 줄이고, 수신단의 재정렬버퍼 (Reordering Buffer)와 립싱크 버퍼의 크기를 3 프레임으로 처리하여 종단간 지연시간을 최소로 하였다. 실험결과에서 종단간 지연시간이 100 ms이하를 유지하고 오디오와 비디오의 립싱크 제어를 하였다.

• 한국정밀공학회지
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• 제14권4호
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• pp.88-96
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• 1997

This paper suggests a new non-linear friction compensation for digital control systems. This control adopts a hysteresis nonlinear element which can introduce the phase lead of the control system to compensate the phase delay comes from the inherent time delay of a digital control. A proper Lyapunov function is selected and the Lyapunov direct method is used to prove the asymptotic stability of the suggested control.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.721-724
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• 2000

This paper has been demonstrated to be essential to successful telemanipulator control when the communication delay between master arms in the operator control station and telemanipulators in the remote site. This paper includes the human dynamics to generate a control command, the monitoring force feedback in order to robust under short time delays and the controller not to requre the derivative of interaction forces. Simulation results suggest that, the proposed control system should be superior to conventional systems in terms of performance and robustness under short time delays.