• 대한전기학회논문지
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• 제45권1호
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• pp.131-138
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• 1996

In this paper, we consider an iterative learning control system(ILCS) consisting of an iterative learning controller, a feedback controller and a controlled plant in the frequency domain. At first, we review the convergence of ILCS. And we give some design guidelines of the ILCS using a nominal model of the plant. Then we present the structured and the unstructured uncertainty bound which guarantees the convergence of the designed iterative learning controller. In particular, we analyze the relationship between the convergence and the magnitude and phase uncertainties. In order to show the usefulness of the proposed analysis and design guidelines, we present some simulation examples. (author). 13 refs., 5 figs.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.71.5-71
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• 2001

This paper presents the vibration control of a flexible intelligent beam with added mass. The materials which is a glass fiber reinforced(GFR) thermoplastic composite is employed to achieve vibration characteristics according to added mass induced end of composite beam. In the experiments of forced vibration control, the -controller are employed to achieve vibration suppression in forced vibration situations. Also, in the controller design, 1st and 2nd´s natural frequencies are considered in the modeling, because robust control theory which has robustness to structured uncertainty is adopted to suppress the vibration. By designing a controller using mu-synthesis, robust performance against measurement noise, various modeling.

• 제어로봇시스템학회논문지
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• 제7권11호
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• pp.896-903
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• 2001

This study investigates the use of mixed $H_2/H_{$\infty}$ and $\mu$-synthesis to construct a robust controller for the benchmark problem. The model treated in the problem is a coupled three-inertial system that reflects the dynamics of mechanical vibrations. This kind of problem requires to be satisfied the robust performance (both in the time and frequency-domain specifications). We, first, adopt the mixed $H_2/H_{$\infty}$ theory to design a feedback controller K(s). Next, $\mu$-synthesis method is applied to the overall system to make use of structured parametric uncertainty. This process permits higher levels of controller authority and reduces the conservativeness of the controller. Finally, the feedforward controller is also used to improve the transient response of the output. We confirm that all design specifications except a complementary sensitivity condition can be achieved.

• 한국정보시스템학회지:정보시스템연구
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• 제29권2호
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• pp.1-26
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• 2020

Purpose This study empirically investigates the impact of information technology(IT) investments on the financial and non-financial performance of a manufacturing firm. We examined the interaction effects of IT investments and strategic applications levels of information systems(IS). This study also demonstrated the three-way interaction effects of IT investments, levels of IS strategic applications, and perceived environmental uncertainty(PEU). Design/methodology/approach For this study, empirical data were collected from 98 manufacturing firms with the structured questionnaires. The data were analyzed with multiple regression models, and partial derivatives were utilized to identify the directions of the impact. Findings From the empirical results, it was found that when both the levels of IS strategic applications and the degrees of IT investments are high, the ratios of the costs of goods sold to total sales(RCGS) and the labor costs to total sales(RLCS) are decreased, as it were, the performance of a firm is improved. However, it was observed that when the levels of strategic IS are low, the high degrees of IT investments do not contribute to the improvement of a performance. The results showed that when the levels of strategic IS are high, the high degrees of IT investments incur the high RSAE not low RSAE. When PEU is considered, the empirical results showed that under the low degrees of PEU, the IT investments under high levels of strategic IS applications (strategic IT investments) improve the performance, as it were, low RCGS, and high degrees of perceived financial and non-financial performance. However, under high PEU, it was observed that high degrees of strategic IT investments do not increase the performance. When PEU is high, the strategic IT investments reduce RSAE, and under low PEU, RSAE is increased.

• 한국융합학회논문지
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• 제8권12호
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• pp.265-274
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• 2017

본 논문은 빅데이터 분석 교육의 문제점을 고찰해 그 개선 방안을 제시한다. 빅데이터의 특성은 V3에서 V5로 진화하고 있다. 이에 빅데이터 분석 교육도 V5를 감안한 데이터 분석 교육이 되어야 한다. 작금 불확실성의 증대는 데이터 분석의 리스크를 증가시키기에 내적 외적 구조화/비구조화 데이터를 비롯해 교란 요인마저 분석할 때 데이터의 신뢰성은 증가될 수 있다. 그리고 평판분석을 활용할 때 범하기 쉬운 오류가 가변성과 불확실성에 대한 상황 인식이다. 가변성의 측면을 고려해, 다양한 변수와 옵션에 의한 불확실성의 상황을 인식하고 대비한 데이터 분석이 이뤄질 때 데이터에 대한 신뢰성과 정확성은 증가할 수 있다. 사회관계망 분석에서 학생들과 일반 연구자들이 주로 활용하는 것이 텍스톰과 노드엑셀의 노드 분석이다. 사화관계망 분석은 매개중심성에 의한 상황 분석을 통해 다크 데이터를 찾아 이상 현상을 감지하고 현 상황을 분석하여 유용한 의미를 얻고 미래를 예측할 수 있어야 한다.

• 전자공학회논문지T
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• 제36T권3호
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• pp.41-49
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• 1999

본 논문에서는 μ-합성법으로 제어기를 설계하여 센서와 구동부가 동일위치에 있지 않은(noncollocated) 탄성-질량 시스템에 적용한다. 스프링 상수값과 제어대상의 부하 질량은 불확실하다고 가정한다 매개변수 불확실성을 포함하고 있는 제어대상은 상태 공간 방정식, 특히 묘사형(descriptor form)을 사용하여 모델링 한다. μ-합성법으로 설계된 H/sub ∞/ 제어기를 표준 H/sub ∞/ 제어기와 비교한다. 두 개의 H/sub ∞/ 제어기 성능을 비교하기 위해, μ-합성 제어기가 구조적 불확실성을 가지고 있다는 것을 제외하고는 서로 동일한 하중함수를 가지고 설계한다. 표준 H/sub ∞/ 제어기와 비교하여 설계된 제어기는 만족스러운 강건 안정성과 강건 성능을 가지는 것을 시뮬레이션과 실험을 통해 확인한다.

• 전기학회논문지
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• 제67권3호
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• pp.419-426
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• 2018

An useful and effective design method for the gas identification system is presented in this paper. The proposed gas identification system adopts hierarchical structure with two level rule base combining fuzzy sets with rough sets. At first, a hybrid genetic algorithm is used in grouping the array sensors of which the measured patterns are similar in order to reduce the dimensionality of patterns to be analyzed and to make rule construction easy and simple. Next, for low level identification, fuzzy inference systems for each divided group are designed by using TSK fuzzy rule, which allow handling the drift and the uncertainty of sensor data effectively. Finally, rough set theory is applied to derive the identification rules at high level which reflect the identification characteristics of each divided group. Thus, the proposed method is able to accomplish effectively dimensionality reduction as well as accurate gas identification. In simulation, we demonstrated the effectiveness of the proposed methods by identifying five types of gases.

• 제어로봇시스템학회논문지
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• 제8권7호
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• pp.539-546
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• 2002

This paper presents a new direct seek control scheme that provides fast data access capability and robust performance for high-speed rotational optical disk drives (ODD). When a disk is rotating at a high speed to obtain fast data transfer in ODD, the magnitude and frequency of velocity disturbance caused by eccentric rotation of the disk increase in proportion to the rotational speed of the disk. Such disturbances make it almost impossible for the conventional seek control scheme to achieve stable and satisfactory seek performance. We analyze the problems that may arise when the conventional seek control scheme is applied to the high-speed rotational ODD and propose a new direct seek control scheme that will solve such problems. In the proposed scheme, a seek control system is designed such that its performance is guaranteed for a set of plants with parameter perturbations. The performance of the proposed seek control scheme is shown by experiments using a high-speed rotational ODD.

• International Journal of Contents
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• 제7권1호
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• pp.58-64
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• 2011

This paper is concerned with simulation exercises used to train key response agencies for crisis situations. While 'multi-agency' simulations are increasingly acknowledged as a necessary and significant training tool for emergency response organisations, many current crisis simulations are still focused on the revision of existing response plans only. However, a crisis requires a rapid reaction, yet in contrast to an 'emergency', the risks for critical decision makers in crisis situations are difficult to measure, owing to their ill-structure. In other words, a crisis situation is likely to create great uncertainty, unfamiliarity and complexity, and consequently should be managed by adaptive or second order expertise and techniques, rather than routine or structured responses. In this context, the paper attempts to prove that the current practices of simulation exercises might not be good enough for uncertain, unfamiliar, and complex 'crisis' situations, in particular, by conducting case studies of two different underground fire crises in Korea (Daegu Subway Fire 2003) and the UK (King's Cross Fire 1987). Finally, it is suggested that the three abilities: 'flexibility', 'improvisation' and 'creativity' are critical in responding to a crisis situation.

• 한국지진공학회논문집
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• 제10권2호
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• pp.83-90
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• 2006

건물의 능동 진동 제어에 있어서 제어기의 제어입력의 포화와 건물의 파라미터 불확실성을 동시에 고려하는 제어 방법이 필요하다. 저자들의 이전 논문에서는 제어 입력에 포화가 존재하는 불확실한 선형 시불변계에 대하여 강인 안정성과 제어 성능이 보장되는 강인 포화 제어기를 제안하였다. 본 논문에서는 능동 질량 감쇠기 (AMD)가 설치된 건물의 능동 진동 제어에 대한 제안된 강인 포화 제어기의 유용성을 실험적으로 검증한다. 실험은 유압식 AMD가 설치된 2층의 건물 모형에 대하여 수행된다.