• 대한기계학회논문집
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• 제17권7호
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• pp.1678-1685
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• 1993

This paper considers a time delay control of noncolocated flexible mechanical systems in discrete time domain. A stability criterion suggested in the previous paper is,extended in the consideration of infinite mode property of flexible systems and finite control sampling frequency. Based on the stability criterion, the one step advanced discrete time derivative control is suggested, which can stabilize infinite number of modes of a flexible system. The sensitivity analysis shows the robustness of the one step advanced control to the system parameter uncertainties and time delay errors. Application to a simply supported beam verifies the extended stability criterion and the effectiveness of the one step advanced D-control.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.326-326
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• 2000

Continuous time system deadbeat controller(CdbC) has been studied mainly since 1992 especially by Japan researchers. They suggested delay elements. These elements stem from the finite Laplace Transform which is the starting point in deadbeat control system design in continuous time system. Every transfer function is established by these elements. From some conditions such as internal model stability and peasibility of a CdbC controller. unknown polynomials or coefficients can be calculated. In this paper, optimal pole placement of the closed loop system is suggested. From this. a CdbC controller with lower order can be obtained which attains the same level of weighted sensitivity function's H$_{\infty}$ norm used as a measure of the robustness property as existing CdbCs.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.237-237
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• 2000

In this paper, The modified dead-time compensator for plants with an integrator and long dead time is proposed. The design procedure takes account of the closed-loop performance and robustness. The tuning of the controller can be done using some information about the plant and its uncertainties. The proposed controller is compared to others recently presented in the literature. Some simulation results verify good closed-performance and robustness of the proposed DTC.

• Journal of Electrical Engineering and Technology
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• 제11권2호
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• pp.320-328
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• 2016

The introduction of renewable energy sources into the AC grid can change and weaken the strength of the grid, which will in turn affect the stability and robustness of the doubly-fed induction generator (DFIG) wind farm. When integrated with weak grids, the DFIG wind turbine with vector power control often suffers from poor performance and robustness, while the DFIG wind turbine with synchronized control provides better stability. This paper investigates the critical short circuit ratios of DFIG wind turbine with vector power control and synchronized control, to analyze the stability boundary of the DFIG wind turbine. Frequency domain methods based on sensitivity and complementary sensitivity of transfer matrix are used to investigate the stability boundary conditions. The critical capacity of DFIG wind farm with conventional vector power control at a certain point of common coupling (PCC) is obtained and is further increased by employing synchronized control properly. The stability boundary is validated by electromagnetic transient simulation of an offshore wind farm connected to a real regional grid.

• 한국구조물진단유지관리공학회 논문집
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• 제21권5호
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• pp.108-116
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• 2017

본 연구는 연쇄붕괴 저항성능 평가 시 기둥의 순간적인 제거에 따른 동적효과가 반영된 에너지 기반 근사해석의 적용성을 확인하기 위해 내진 설계된 철골모멘트골조의 예제구조물을 대상으로 분석하였으며, 이를 통해 구조 강건성을 산정하여 연쇄붕괴에 대한 민감도를 평가할 수 있는 방법을 제시하였다. 예제구조물에 대한 적용을 통해 비선형 정적해석 결과를 이용한 에너지 기반 근사해석과 직접동적해석에 대한 결과가 잘 일치하는 것을 검증하였으며, 다른 구조시스템을 가지는 건물의 연쇄붕괴에 대한 구조적 내력성능을 비교하기 위한 수단으로 구조물의 민감도를 평가하였다. 이는 비정상하중에 대하여 구조물이 연쇄붕괴에 저항할 수 있는 최대보유 잔류내력 성능인 구조 강건성을 이용하였고, 본 연구에서 제시한 방법을 통해 연쇄붕괴 해석 및 설계에 편리하게 활용될 수 있음을 확인하였다.

• 대한기계학회논문집A
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• 제24권1호
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• pp.215-224
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• 2000

In order to reduce the variation effects of uncertainties in the engineering environments, new robust optimization method, which considers the uncertainties in design process, is proposed. Both design variables and system parameters are considered as random variables about their nominal values. To ensure the robustness of performance function, a new objective is set to minimize the variance of that function. Constraint variations are handled by introducing probability constraints. Probability constraints are solved by the advanced first order second moment (AFOSM) method based on the reliability theory. The proposed robust optimization method has an advantage that the second derivatives of the constraints are not required. The suggested method is examined by solving three examples and the results are compared with those for deterministic case and those available in literature.

• 대한산업공학회지
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• 제34권2호
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• pp.122-139
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• 2008

With the proliferation of in-process measurement technology, autocorrelated data are increasingly common in industrial SPC applications. A number of high performance control charting techniques that take into account the specific characteristics of the autocorrelation through time series modeling have been proposed over the past decade. We present a survey of such methods and analyze and compare their performances for a range of typical autocorrelated process models. One practical concern with these methods is that their performances are often strongly affected by errors in the time series models used to represent the autocorrelation. We also provide some analytical results comparing the robustness of the various methods with respect to time series modeling errors.

• Communications for Statistical Applications and Methods
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• 제2권2호
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• pp.277-287
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• 1995

It is well kmown that the $L_1$-estimator is robust with respect to vertical outliers in regression data, even if it is susceptible to bad leverage points. This article is concerned with the robustness of the $L_1$-estimator. To investigate its robustness against vertical outliers we may find intervals for the value of the response variable within which the $L_1$-estimates do not shange. A procedure for constructing those intervals in multiple limear regression is illustrated in the sensitivity analysis context. And then vertical breakdown point of the $L_1$-estimator is defined on the basis of properties related to those intervals.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.95.2-95
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• 2001

Disturbance observer(DOB) based controller design is one of the most popular methods in the field of motion control. In this paper, a generalized disturbance compensation framework, called as robust internal-loop compensator(RIC) is introduced and an advanced design method of DOB is proposed based on the RIC. Mixed sensitivity optimization problem, which is the main issue of DOB design, is solved through the parameterization of DOB in the RIC framework. Different from conventional methods, Q-filter is separated in the mixed sensitivity optimization problem and the systematic design law for the DOB is proposed. This guarantees the robustness and optimality of the DOB and also enables the design for unstable plants.

• Nuclear Engineering and Technology
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• 제30권4호
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• pp.353-363
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• 1998

The H$_{\infty}$ algorithms of the mixed weight sensitivity is used for the robust design of the reactor power control system. The mixed weight sensitivity method requires the selection of the proper weighting functions for the loop shaping in frequency domain. The complexity of the system equation and the non-convexity of the problem make it very difficult to determine the weighting functions. The genetic algorithm which is improved and hybridized with the simulated annealing is applied to determine the weighting functions. This approach permits an automatic calculation and the resultant system shows good robustness and performance.