• 한국소음진동공학회논문집
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• 제14권12호
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• pp.1330-1337
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• 2004

In this study, the equations of motion of a rigid rotor supported by magnetic bearings are derived via Hamilton's principle, and transformed to a state-space form for control purpose. The optimal motion control of rotor magnetic bearing system based on the LQR(linear quadratic regulator) theory is addressed. New schemes related to the selection of the state weighting matrix Q and the control weighting matrix R involved in the quadratic functional to be minimized are proposed. And the robust control of the system with an LMI(linear matrix inequality) based H$_{\infty}$ theory is dealt with in this paper. Loop shapings of TFM (transfer function matrix) are used to increase the performance of control capability of the system. The control abilities of LQR and H$_{\infty}$ controller are compared by simulation and experimental tests and show that the capability of H$_{\infty}$ controller is superior to that of LQR.

• 한국인터넷방송통신학회논문지
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• 제16권6호
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• pp.103-108
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• 2016

오늘날 도시의 규모가 커지고 기능이 복잡해지고 있으며, 다양한 사람들이 다양한 활동을 하며 살아가고 있다. 또한 도시에서의 사람의 삶은 많은 부분에서 주변의 사람과 연관되어 있다. 그리고 도시의 생활은 다양한 인공적인 활동을 하고 있음을 뜻하며, 이에 따른 소리의 발생이 주변사람에게는 소음공해가 되기도 한다. 이러한 이유에서 사람들로 만들어진 인공소음은 특히 서울의 도심 4대문 안의 도로 주변의 소음은 평균 73㏈가 될 정도로 크다. 그리고 도시에 사라는 사람들은 소음공해에 쉽게 노출되며 특히 집회나 시위현장 또는 홍보를 위해 사용되는 확성기들은 상당한 소음을 발생시키며 이는 다른 사람들에게 스트레스를 유발한다. 더욱이, 집회 및 시위에 관한 법률 등에서 지정하는 확성기 사용 및 규제는 있지만 잘 지켜지지 않는 것이 현실이다. 그리고 최근 법령을 -5㏈를 낮추는 등의 법령기준을 강화하였지만, 여전히 스트레스가 되고 있다. 따라서 집회 및 시위현장의 소음의 크기를 제한하고 규제하는 것 뿐만 아니라, 노출되는 시간을 고려하여 피해를 줄이는 것이 더 효과적인 방법이다. 소음으로 인한 스트레스는 짧은 시간만 노출되더라도 오래도록 지속되며, 이러한 환경에 위치한다면, 소음공간에서 빠르게 벗어나는 것을 권장 하는 것도 본 연구에서 제시하는 피해저감 방안이다.

• 한국경영과학회지
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• 제21권3호
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• pp.159-174
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• 1996

Facing decision-making tasks, managers frequently make judgments, However, since managers are human beings, the fficiency of their judgments is limited. Two major sources of inefficiency in their judgments have been recognized : one is systematic deviations from normatively preferred decisions, so called bias or incorrect intuition, and the other is inconsistency in their judgments, i. e. erratic decision making variance. Rather than bias, variance is really expensive or damaging. Thus, if the inconsistency inmanagers judgments is removed, performance could be by far improved by virtue of the reduced random variance. One of the approaches to improve managerial judgment is to simply bring managers together by effectively moderating the random variance due to inconsistency. Focusing on combining judgments, this paper addresses many relevant issues such as why combining and how to combine judgments, and suggests methods and models to effectively aggregate subjective judgments, We conduct an experiment to validata the effectiveness of combining jugements over individual judgments. Various combining schemes are also evaluated in terms of their prective accuracy. Among them, mean bias based wighting scheme turns out the best. However, when available information is not enough to estimate the expertise of judges, simple and robust equal weighting might be more efficient and productive. This urges an imperative future research on the issue of how many and which ones to combine from a large set of experts.

• 대한전자공학회논문지
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• 제26권4호
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• pp.98-105
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• 1989

선택적인 주파수 특성을 가지고 있는 인간의 시각 시스템(HVS)을 왈쉬함수로 표현되는 아다마르변환 영역에서 적용하였다. 아다마르 기본함수의 주파수 성분을 구하여 시각 시스템을 모델링하였으며 이때 오차측정의 기준으로서 저 전송율 변환 부호화기에서 중요한 요소인 블록 경계상의 오차와 평균자승 오차를 사용한 결과 인간이 가장 높은 감도를 갖는 공간 주파수는 이산 여현 변환의 경우보다 높게 나타났다. 부호화기에서 HVS 모델을 적용하여 시각적 감도가 높거나 중요한 정보만을 전송하고 북호화기에서는 역하중이 없는 방법을 제시하였다. 블록과 블록이 교차하는 영역에서 특히 크게 나타나는 오차를 감소시키기위해 시각적 하중 방법을 사용하였으며 0.8 bpp이하의 전송율에서 인간의 시각 특성에 만족되는 변환부호화를 시험하였다.

• Journal of Communications and Networks
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• 제5권4호
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• pp.328-343
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• 2003

Orthogonal pulse-shape modulation using Hermite pulses for ultra-wideband communications is reviewed. Closedform expressions of cross-correlations among Hermite pulses and their corresponding transmit and receive waveforms are provided. These show that the pulses lose orthogonality at the receiver in the presence of differentiating antennas. Using these expressions, an algebraic model is established based on the projections of distorted receive waveforms onto the orthonormal basis given by the set of normalized orthogonal Hermite pulses. Using this new matrix model, a number of pulse-shape modulation schemes are analyzed and a novel orthogonal design is proposed. In the proposed orthogonal design, transmit waveforms are constructed as combinations of elementary Hermites with weighting coefficients derived by employing the Gram-Schmidt (QR) factorization of the differentiating distortion model’s matrix. The design ensures orthogonality of the vectors at the output of the receiver bank of correlators, without requiring compensation for the distortion introduced by the antennas. In addition, a new set of elementary Hermite Pulses is proposed which further enhances the performance of the new design while enabling a simplified hardware implementation.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.292-295
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• 2003

In this paper, we present static output feedback model predictive tracking control for linear system with uncertainty. The proposed control law is based on integral action form to provide zero o��set for constant command signals and the closed loop stability is guaranteed under linear matrix inequality conditions on the terminal weighting matrix using the decreasing monotonicity property of the performance index. Through simulation examples, we illustrate that the proposed schemes can be appropriate tracking controllers for uncertain system.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.508-513
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• 2003

This paper is concerned with a mixed control with aerodynamic fin and side thrusters applied to an agile missile using two-time scale dynamic inversion and linear time-varying control technique. The nonlinear dynamic inversion method with the weighting function allocates the desired control inputs (aerodynamic fin and side thrusters) to track a reference trajectory, and the time-varying control technique guarantees the robustness for the uncertainties. Closed-loop stability is achieved by the assignment of the extended-mean of these linear time-varying eigenvalues to the left half complex plane. The proposed schemes are validated by nonlinear simulations.

• 전기의세계
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• 제30권12호
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• pp.822-831
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• 1981

Many different schemes of the adaptive observer and controller have been developed for both continuous and discrete systems. In this paper we have presented a new scheme of the reduced order adaptive observer for the single input discrete linear time invariant plant. The output equation of the plant, is transformed into the bilinear form in terms of system parameters and the states of the state variable filters. Using the plant output equation the discrete implicit adaptive observer based on the similar philosophy to Nuyan and Carroll is derived and the parameter adaptation algorithm is derived based on the exponentially weighted least square method. The adaptive model following control system is also constructed according to the proposed observer scheme. The proposed observer and controller are rather than simple structure and have a fast adaptive algorithm, so it may be expected that the scheme is suitable to the practical application of control system design. The effectiveness of the algorithm and structure is illustrated by the computer simulation of a third order system. The simulation results show that the convergence speed is proportinal to the increasing of weighting factor alpha, and that the full order and reduced order observer have similar convergence characteristics.

• 제어로봇시스템학회논문지
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• 제10권10호
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• pp.947-955
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• 2004

This paper is concerned with a mixed control with aerodynamic fin and side thrust control applied to an agile missile using a dynamic inversion and a time-varying control technique. The nonlinear dynamic inversion method with the weighting function allocates the desired control inputs(aerodynamic fin and side thrust control) to achieve a reference command, and the time-varying control technique plays the role to guarantee the robustness for the uncertainties. The proposed schemes are validated by nonlinear simulations with aerodynamic data.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(4)
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• pp.33-36
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• 2002

Multiple Description Coding(MDC) is a technique used to obtain two or more (often correlated) descriptions of a source, which are transmitted over different channels to receiver. Two descriptions of the source support two levels of reconstruction quality. When all the descriptions are received and used in the reconstruction, the source should be reconstructed with acceptable quality. In this work, we consider Multiple Description Scalar Quantizer(MDSQ) to wavelet transform domain. Conventional MDSQ schemes in wavelet domain considered description with equal weights at each sub-bands after quantization. But each sub-bands is unequal contribution to whole image quality. Therefore, we experiment the multiple description with unequal weight in each sub-bands.