• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1901-1904
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• 2003

MPC or model predictive control is representative of control methods which are able to handle physical constraints. Closed-loop stability can therefore be ensured only locally in the presence of constraints of this type. However, if the system is neutrally stable, and if the constraints are imposed only on the input, global aymptotic stability can be obtained; until recently, use of infinite horizons was thought to be inevitable in this case. A globally stabilizing finite-horizon MPC has lately been suggested for neutrally stable continuous-time systems using a non-quadratic terminal cost which consists of cubic as well as quadratic functions of the state. The idea originates from the so-called small gain control, where the global stability is proven using a non-quadratic Lyapunov function. The newly developed finite-horizon MPC employs the same form of Lyapunov function as the terminal cost, thereby leading to global asymptotic stability. A discrete-time version of this finite-horizon MPC is presented here. The proposed MPC algorithm is also coded using an SQP (Sequential Quadratic Programming) algorithm, and simulation results are given to show the effectiveness of the method.

• Journal of Electrical Engineering and Technology
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• 제12권5호
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• pp.1719-1728
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• 2017

Recent concerns about environmental conditions have triggered the growing interest in using green energy resources. These sources of energy, however, bring new challenges mainly due to their uncertainty and intermittency. In order to alleviate the concerns on the penetration of intermittent energy resources, this paper investigates impacts of realizing demand-side potentials. Among different demand-side management programs, this paper considers demand response wherein consumers change their consumption pattern in response to changing prices. The research studies demand response potentials from different load sectors on generation system well-being. Consumers' sensitivity to time-varying prices is captured via self and cross elasticity coefficients. In the calculation of well-being indices, sequential Monte Carlo simulation approach is accompanied with fuzzy logic. Finally, IEEE-RTS is used as the test bed to conduct several simulations and the associated results are thoroughly discussed.

• Ocean Systems Engineering
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• 제6권4호
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• pp.345-362
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• 2016

This study aims to develop the numerical method to estimate level ice impact load and investigate the dynamic interaction between an arctic Spar with sloped surface and drifting level ice. When the level ice approaches the downward sloped structure, the interaction can be decomposed into three sequential phases: the breaking phase, when ice contacts the structure and is bent by bending moment; the rotating phase, when the broken ice is submerged and rotated underneath the structure; and the sliding phase, when the submerged broken ice becomes parallel to the sloping surface causing buoyancy-induced fictional forces. In each phase, the analytical formulas are constructed to account for the relevant physics and the results are compared to other existing methods or standards. The time-dependent ice load is coupled with hull-riser-mooring coupled dynamic analysis program. Then, the fully coupled program is applied to a moored arctic Spar with sloped surface with drifting level ice. The occurrence of dynamic resonance between ice load and spar motion causing large mooring tension is demonstrated.

• 한국안전학회지
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• 제7권2호
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• pp.71-79
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• 1992

This paper presents a least-square algorithms of lattice structures and their use for adaptive prediction of time series generated from the dynamic system. As the view point of adaptive prediction, a new method of Identification of dynamic characteristics by means of estimating the parameters of linear auto regressive model is proposed. The fast convergence of adaptive lattice algorithms is seen to be due to the orthogonalization and decoupling properties of the lattice. The superiority of the least-square lattice is verified by computer simulation, then predictor coefficients are computed from the linear sequential time data. For the application to the dynamic characteristic analysis of unknown system, the transfer function of ideal system represented in frquency domain and the estimated one obtained by predicted coefficients are compared. Using the proposed method, the damping ratio and the natural frequency of a dynamic structure subjected to random excitations can be estimated. It is expected that this method will be widely applicable to other technical dynamic problem in which estimation of damping ratio and fundamental vibration modes are required.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 D
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• pp.2479-2481
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• 2000

It is the time-varying dissolved oxygen(DO) dynamics that requires controlling for maintaining the DO concentration in the aeration tank. Many linear controllers have thus been applied. Because of the nonlinearity of the oxygen transfer function together with the time-varying respiration rate, however, the linear controllers are found to poorly perform in many cases. To overcome this limitation, a number of advanced controlling techniques have been developed and applied. In this study, designed GA-PI Controller using genetic algorithm(GA). Genetic algorithms(GAs) are search algorithms based on the mechanics of natural selection and natural genetics. As result of computer simulation, GA-PI controller shows the better control performance especially under the condition of the continuously changing DO set-point. This result represents that GA-PI controller can be a good measure to control the DO concentration in the SBR process which requires the sequential DO set-point change to accomplish the nitrification and denitrification in a single reactor.

• 전기학회논문지
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• 제68권1호
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• pp.44-51
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• 2019

Tunnel Boring Machine's Technology has depends mostly on imports, currently domestic technology development was proceeding. There are many technologies in this field, above all, the large-capacity motor drive technology required for excavation is one of the core technologies. In particular, when several large motors are simultaneously starting, there are many problems due to a large starting current at that time, and it is difficult to design and operate a power receiving facility. In this paper, A method of reducing the starting current by using the regenerative power generated by the deceleration of the motor has been studied. To verify this proposal, we designed the induction motor controller using CAE based power simulation tool and verified the results of the proposed method by applying the reduced model. As a result, it is possible to reduce the maximum starting current and shorten the start-up time. Moreover, even if several motors are connected to one bank, it is proved that the method can be efficiently operated by using the sequential braking / starting sequence. In the case of a power system in which a large capacity electric motor such as a tunnel excavation system is driven, the results of this study are expected to be a stable and effective method for solving the start-up current problem and designing the power receiving facility.

• 응용통계연구
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• 제35권1호
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• pp.63-75
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• 2022

본 논문은 Wang과 Samworth (2018)가 제안한 성근 프로젝션 방법을 개선하여 MOSUM을 이용하여 고차원의 시계열데이터에 존재하는 다중 평균 변화점을 추정하는 방법에 대해서 제안한다. 제안한 방법은 국소방법으로 다중 변화점을 동시에 찾을 수 있어 순차적 오류를 최소화 할 뿐만 아니라 평균이 상쇄되는 경우에도 변화점을 추정하는 장점을 지니고 있다. 또한 데이터 의존적인 방법으로 블록 와일드 붓스트랩 방법을 활용하여 임계점을 찾는 방법을 제안한다. 모의 실험을 통해 제안한 방법이 좋은 성능을 보임을 확인하였으며 S&P 500 지수를 구성하는 개별 기업들의 금융 자료에 적용하여 최근 6년간 네 번의 변화점을 찾았다.

• 한국정보통신학회논문지
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• 제13권7호
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• pp.1444-1452
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• 2009

일상적인 상황이 주로 시간을 고려한 일정에 따라서만 발생한다고 가정하면 각 상황별 확률분포함수에 기반한 데이터 생성법은 효과적이다. 하지만, 사람들은 상황을 인식하거나 판단할 때, 이전 상황을 고려하여 현재 상황을 미루어 짐작하거나 결정하는 경우도 흔하다. 본 논문에서 제안한 상황 전파 네트워크는 상황 인식 및 결정에서 이전 상황이 현재 상황에 미치는 영향을 고려하는 것과 유사하게 상황발생 확률분포함수를 보상해 줌으로써 상황의 전개가 연속적이면서 자연스러운 흐름을 갖도록 해준다. 본 논문에서는 평범한 직장인이 집이라는 공간에서 발생시키는 상황 데이터를 생성하는 모델을 제안하였고, 모의실험을 통해 상황 전파 네트워크가 상황의 자연스러운 흐름에 얼마나 영향을 기여하는지 확인하였으며, 특히, 순차적 상황 모호성과 충돌성 지표를 새롭게 정의하여 제안한 상황 데이터 생성 모델을 평가했다. 결론적으로 상황 전파 네트워크를 결합시켰을 경우, 확률 모델만을 사용했을 때보다 순차적 상황 모호성은 6.45% 상황 충돌성은 4.60% 감소함을 확인했다.

• Journal of Astronomy and Space Sciences
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• 제32권3호
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• pp.229-235
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• 2015

We estimated the orbit of the Communication, Ocean and Meteorological Satellite (COMS), a Geostationary Earth Orbit (GEO) satellite, through data from actual optical observations using telescopes at the Sobaeksan Optical Astronomy Observatory (SOAO) of the Korea Astronomy and Space Science Institute (KASI), Optical Wide field Patrol (OWL) at KASI, and the Chungbuk National University Observatory (CNUO) from August 1, 2014, to January 13, 2015. The astrometric data of the satellite were extracted from the World Coordinate System (WCS) in the obtained images, and geometrically distorted errors were corrected. To handle the optically observed data, corrections were made for the observation time, light-travel time delay, shutter speed delay, and aberration. For final product, the sequential filter within the Orbit Determination Tool Kit (ODTK) was used for orbit estimation based on the results of optical observation. In addition, a comparative analysis was conducted between the precise orbit from the ephemeris of the COMS maintained by the satellite operator and the results of orbit estimation using optical observation. The orbits estimated in simulation agree with those estimated with actual optical observation data. The error in the results using optical observation data decreased with increasing number of observatories. Our results are useful for optimizing observation data for orbit estimation.

• 한국항행학회논문지
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• 제24권3호
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• pp.184-191
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• 2020

항공용 SIL은 항공전자시스템의 통합 및 검증에 사용되는 통합시험환경이다. 항공용 SIL에는 여러 가지 제약으로 인해 항공기에 탑재되는 장비를 직접 연동할 수 없을 때 장비의 소프트웨어 모델이 필요하다. 지금까지 항공기 개발에 적용한 항공용 SIL의 소프트웨어 모델은 표준화된 방법 없이 일반적인 소프트웨어 개발 방법의 적용으로 재사용이 어려워 소프트웨어 모델 재사용을 위한 프레임워크의 필요성이 제기되었다. 이러한 항공용 SIL 모델의 표준화된 모델링 방법을 위해 DEVS (discrete event system specification) 형식론을 채용하였다. DEVS 형식론은 이벤트 구동(event-driven) 알고리즘이며 이는 기존의 항공용 SIL에 적용되는 절차적이고 반복적인 알고리즘과 어울려 동작하기 힘들다. 이에 본 논문에서는 항공용 SIL 모델의 특징과 기존 방식이 가지는 한계를 보완하고 모델의 재사용성을 극대화할 수 있는 이벤트 기반의 모델링 방법과 실시간 시뮬레이션 방법을 제안한다.