• Economic and Environmental Geology
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• v.27 no.1
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• pp.41-47
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• 1994

A fast Hankel transform (FHT) algorithm (Anderson, 1982) is applied to numerical evaluation of many Green's tensor integrals encountered in three-dimensional electromagnetic modeling using integral equations. Efficient computation of Hankel transforms is obtained by a combination of related and lagged convolutions which are available in the FHT. We express Green's tensor integrals for a layered half-space, and rewrite those to a form of related functions so that the FHT can be applied in an efficient manner. By use of the FHT, a complete or full matrix of the related Hankel transform can be rapidly and accurately calculated for about the same computation time as would be required for a single direct convolution. Computing time for a five-layer half-space shows that the FHT is about 117 and 4 times faster than conventional direct and multiple lagged convolution methods, respectively.

• Journal of the korean Society of Automotive Engineers
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• v.13 no.5
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• pp.73-80
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• 1991

Air/fuel ratio control system for gasoline engines has been analyzed to determine the control gain of the system. In this analysis the engine is modelled to be a simple time delaying element and the ramp-and-jump method is used to control air/fuel ratio. The result shows that it is necessary to measure the air flow rate accurately to enhance the control performance. And also it is shown that the control gain must be determined in some bounded region to meet the fast dynamic response and high catalyst conversion efficiency together.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.2
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• pp.163-169
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• 2000

From the viewpoint of the cost effective design of power conversion systems, it is very important to fully u utilize the CillTent capacity of power devices over all circumstances. Therefore this paper deals with the l practical design of digital CillTent controller to meet the requirements of fast and overshoot free control r response over the varying control voltage bOlmds, the accompanied computational delay, and the system U W1certainties. The proposed controller consists of high gain PI control schemes using both the conditional i integrator and the modified delay compensator. The simulation and experimental results show the validity of t the proposed controller.

• Journal of Advanced Marine Engineering and Technology
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• v.14 no.3
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• pp.52-60
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• 1990

제어입력에 무시하지 못할 정도의 시간지연이 있는 시스템에 있어서의 강인한 제어기를 설계하고 실현하는 문제를 다루었다. 본 논문에서 제안하는 제어기를 설계하기 위하여 전향 방향에 적분기 하나를 추가하고 빠른 응답 특성을 주기 위하여 상태변수 $x_1$ 대신 오차신호 y-$y_r$를 궤환 하도록 하였으며 여기서 일어날 수 있는 오우버슈터를 줄이기 위하여 Integral reset scheme을 이용하였다. 제어기 실현을 위하여서는 궤환되어지는 모든 상태변수의 측정이 요구되나 실제 제어 문제에서는 경제적, 기술적인 문제로 그렇지 못하므로 측정 불가능한 상태변수는 상태관측기를 구성하여 이용하도록 하였다.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.45.1-45.1
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• 2010

한국천문연구원과 일본 국립천문대는 공동으로 한일공동VLBI상관기(Korea-Japan VLBI Correlator, KJJVC)를 개발하였다. 이 상관기는 최대 16 관측국에 대하여 16 세트의 자기상관 및 120 세트의 상호상관을 계산할 수 있다. 각 관측국당 최대 8,192 Mbits/sec의 입력 데이터를 처리할 수 있으며, 8,192개의 주파수채널을 갖는 상관 스펙트럼을 약 25.4 밀리초~수초의 적분 시간으로 출력할 수 있는데, 최대 상관 출력 속도는 1.4GB/sec이다. 한편, 이 상관기는 한국우주전파관측망(KVN) 뿐만 아니라 동아시아VLBI관측망 및 우주공간VLBI관측망의 관측 데이터도 처리할 수 있도록 설계 제작되었으며, 최대 지연 추적 범위는 ${\pm}35,000km$이며, 보상 가능한 최대 기선 속도는 7.5km/sec이다. 현재 다른 VLBI관측망에서 사용하고 있는 타 상관기의 경우 지연은 2차 미분까지 보상하고, 프린지 위상은 3 단계로 보상하고 있는 것에 비하여, 한일공동VLBI상관기에서는 지연은 3차 미분까지 보상하여 지연 잔차를 최소화하고 프린지 위상은 16 단계로 세분하여 보상 수준의 정밀도를 최대화하였다. 이러한 지연 보상 및 프린지 멈춤 알고리즘을 상세히 소개하고 그 특성 및 장점을 보고한다.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.6
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• pp.753-759
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• 2006

Integrating processes are frequently encountered in process industries. In this paper, new tuning formulae of the PID controllers for set-point tracking and load disturbance rejection are presented for integrating processes involving time delay. First, the controller parameter sets are tuned using a real-coded genetic algorithm (RCGA) such that performance criterion(IAE, ISE or ITSE) is minimized. Then, tuning rules are addressed using tuned PID parameter sets. tuning model and another RCGA. The performances of the proposed rules are tested on two processes.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.3
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• pp.457-462
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• 2016

In this paper, we consider the stability of time-delayed linear systems. To derive an LMI form of result, the integral inequality is essential, and Jensen's integral inequality was the best in the last two decades until Seuret's integral inequality is appeared recently. However, these two are proportional to the inverse of integration interval, so another integral inequality is needed to make it in the form of LMI. In this paper, we derive an integral inequality which is proportional to the integration interval which can be easily converted into LMI form without any other inequality. Also, it is shown that Seuret's integral inequality is a special case of our result. Next, based on this new integral inequality, we derive a stability condition in the form of LMI. Finally, we show, by well-known two examples, that our result is less conservative than the recent results.

• Proceedings of the IEEK Conference
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• 2003.07c
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• pp.2803-2806
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• 2003

In this paper considers the design of the effective controllers for the plant with an integrator and a long dead time. The structure of the new DTC(Dead Time Compensator) that has an additive filter is proposed. Our DTC shows the improved performance in set-point response and disturbance rejection. Especially the bad effect of the long dead time in the disturbance rejection is fairly reduced by using the additive filter. illustrative examples are provided to show the availability of the proposed controller.

• Electronics and Telecommunications Trends
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• v.15 no.5 s.65
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• pp.86-93
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• 2000

지하 탐사용 레이더를 이용하여 지하에 매설된 구조물의 위치를 파악하고 그에 따른 근사 이미지의 추출 방법을 제안하였다. 기본원리는 구조물에 의해 산란되어 수신 안테나로 유입되는 펄스신호의 지연시간과 크기를 측정하는 데 있으며, 측정의 실용성을 위하여 레이더 탐색경로에 따른 수신신호의 절대치 적분 방법을 사용하였다. 일반적으로 지하매질은 침투 주파수에 따라서 다양한 분산 및 손실 특성을 나타내는데, 이러한 매질 특성은 다항 Debye 모델을 이용하여 기술되었다. 3차원 전파(電波) 전파(傳播)를 위한 시뮬레이션에는 FDTD(Finite Difference Time Domain) 방법을 사용하였다.

• Korean Chemical Engineering Research
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• v.49 no.5
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• pp.565-570
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• 2011

In this paper, the analytical tuning rules of the proportional-integral-derivative (PID) controller have been derived for a broad class of stable, integrating, and unstable processes without time delay. On the basis of the renowned internal model control (IMC) design principles and the two-degree-of-freedom (2DOF) control structure, the proposed method can be effectively used for obtaining the enhanced performances of both the disturbance rejection as well as the set-point tracking problems, since the design scheme is simple, straightforward, and can be easily implemented in the process industry. Several processes without time delay are employed to demonstrate the improved closed-loop performance of the proposed controller design in compared with the other well-known design methods in terms of the same degree of robustness.