• 자동차안전학회지
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• 제14권4호
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• pp.53-59
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• 2022

This paper describes an integrated control of torque vectoring and rear wheel steering using model predictive control. The control objective is to minimize the yaw rate and body side slip angle errors with chattering alleviation. The proposed model predictive controller is devised using a linear parameter-varying (LPV) vehicle model with real time estimation of the varying model parameters. The proposed controller has been investigated via computer simulations. In the simulation results, the performance of the proposed controller has been compared with uncontrolled cases. The simulation results show that the proposed algorithm can improve the lateral stability and handling performance.

• The Journal of the Acoustical Society of Korea
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• 제16권2E호
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• pp.32-37
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• 1997

This paper proposes a isolated speech recognition method of Korean digits using a TDNN(Time Delay Neural Network) which is able to recognizc time-varying speech properties. We also make an investigation of effect on network parameter of TDNN ; hidden layers and time-delays. TDNNs in our experiments consist of 2 and 3 hidden layers and have several time-delays. From experiment result, TDNN structure which has 2 hidden-layers, gives a good result for speech recognition of Korean digits. Mis-recognition by time-delays can be improved by changing TDNN structures and mis-recognition separated from time-delays can be improved by changing input patterns.

• 제어로봇시스템학회논문지
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• 제17권3호
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• pp.258-263
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• 2011

In the bilateral tele-operation system, time delay may be a critical problem. Even if system modeling error or time delay occurs, when applied to wave transformation system, the system's stability can be achieved. Using the characteristic b which is an important parameter of wave transformation, the system can display robust performance for time delay. However, since assuming and that the time delay was fixed developing a theory, a stability cannot be guaranteed about the time-varying delay. Therefore, In the paper, Therefore, in this paper, we studied for the method that controls this by applying the fuzzy algorithm which surveyed the timevarying delay characteristics and can adjust the b according to it adaptively.

• 경제분석
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• 제17권2호
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• pp.27-55
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• 2011

최근 금융시장의 변동성이 현저하게 증폭되면서 이에 대한 원인으로 금융시장의 군집 행동에 대한 이론적 연구가 활발하게 진행되고 있지만 군집행동의 시계열적 특성을 파악할 수 있는 실증적 연구는 거의 없었다. 따라서 본 연구는 연속신념시스템(continuous beliefs system)의 이론적 확장을 통해 군집행동을 시계열적으로 측정할 수 있는 군집행동 파라미터를 도출하였으며 이를 추정하기 위한 계량모형을 제안하였다. 또한 이 모형의 효율적 추정을 위해 MCMC 추정법을 적용하였다. KOSPI와 DOW 지수월별자료를 이용한 실증분석 결과에 의하면 미국보다 우리나라 주식시장의 군집행동이, 그리고 글로벌 금융위기 전보다 글로벌 금융위기 이후에 군집행동이 강하게 나타났다. 또한 글로벌 금융위기로 인해 군집행동의 변동성(표준편차)이 증가하였으며 군집행동은 수익률 변동성과는 달리 지속적인 자기상관을 유지하지 않았다. 이런 결과는 군집행동이 금융시장을 불안하게 만드는 한 원인이 될 수 있음을 나타낸다.

• International Journal of Control, Automation, and Systems
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• 제4권6호
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• pp.689-696
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• 2006

This paper presents a new algorithm for the closed-loop $H_{\infty}$ composite control of weakly coupled bilinear systems with time-varying parameter uncertainties and exogenous disturbance using the successive Galerkin approximation(SGA). By using weak coupling theory, the robust $H_{\infty}$ control can be obtained from two reduced-order robust $H_{\infty}$ control problems in parallel. The $H_{\infty}$ control theory guarantees robust closed-loop performance but the resulting problem is difficult to solve for uncertain bilinear systems. In order to overcome the difficulties inherent in the $H_{\infty}$ control problem, two $H_{\infty}$ control laws are constructed in terms of the approximated solution to two independent Hamilton-Jacobi-Isaac equations using the SGA method. One of the purposes of this paper is to design a closed-loop parallel robust $H_{\infty}$ control law for the weakly coupled bilinear systems with parameter uncertainties using the SGA method. The other is to reduce the computational complexity when the SGA method is applied to the high order systems.

• 동력기계공학회지
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• 제9권4호
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• pp.175-180
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• 2005

Incorrections between model and plant are parameter, system order uncertainties and modeling error due to disturbance like friction. Therefore to achieve a good tracking performance, adaptive discrete time sliding mode tracking controller is used under time-varying desired position. Based on the diophantine equation, a new discrete time sliding function is defined and utilized for the control law. Robustness is increased by using both a recursive least-square method and a sliding function-based nonlinear feedback. The effectiveness of the proposed control algorithm is proved by the results of simulation and experiment.

• 한국산학기술학회논문지
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• 제10권12호
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• pp.3622-3625
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• 2009

본 논문은 고정 슬라이딩면을 갖는 가변 구조 제어기의 단점인 도달영역에서의 파리미터의 불확실성과 외부 외란에 대한 민감성을 감소시키는 방안으로 고정 슬라이딩면 대신 비선형 슬라이딩면을 제시한다. 비선형 슬라이딩면을 통하여 시스템 상태 궤적이 초기 위치에서부터 평형점에 이르기까지 외란과 파라미터의 불확실성에 강인하게 되며 아울러 고정 슬라이딩면까지의 도달시간 뿐만 아니라 평형점까지의 도달시간도 감소하게 되는 특성을 보이고자한다. 제안된 제어 구조의 효과는 시뮬레이션을 통해 증명하였다.

• 대한의용생체공학회:의공학회지
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• 제34권3호
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• pp.117-122
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• 2013

Hyaluronic acid(HA) microbeads were synthesized by dropping the sodium hyaluronate(Streptococcus) solutions in NaOH into a solution mixture of divinyl sulfone(DVS) in 2-methyl-1-propanol, followed by stirring, cleaning and drying process at room temperature. The initial experimental conditions are crosslinking time(CLTi) of 5 h, crosslinking temperature(CLTe) of room temperature, injection air pressure(IAPr) of 5 psi, and DVS concentration( DVSc) of 0.2 vol%, respectively. Then, parametric studies were performed by varying the parameters to investigate the morphology, the porosity, the swelling ratio and the size of the beads. The microbead size pattern was not regular to function of the degree of crosslink. It was observed that the swelling ratio, the degree of crosslink, and the pore size can be controlled by adjusting the CLTi, CLTe and DVSc. Among the parameters investigated, the smallest bead size can be achieved by varying the CLTi parameter. The lowest swelling ratio, as an indication of the highest degree of crosslink, can be obtained by varying CLTe.

• Asia pacific journal of information systems
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• 제26권3호
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• pp.427-448
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• 2016

The stochastic phenomena of traffic network condition, such as traffic speed and density, are affected not only by exogenous traffic control but also by endogenous changes in service time during congestion. In this paper, we propose a mixed M/G/1 queuing model by introducing a condition-varying parameter of traffic congestion to reflect structural changes in the traffic network. We also develop congestion indices to evaluate network efficiency in terms of traffic flow and economic cost in traffic operating system using structure-changing queuing model, and perform scenario analysis according to various traffic network improvement policies. Empirical analysis using Korean highway traffic operating system shows that our suggested model better captures structural changes in the traffic queue. The scenario analysis also shows that occasional reversible lane operation during peak times can be more efficient and feasible than regular lane extension in Korea.

• Journal of Electrical Engineering and Technology
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• 제4권2호
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• pp.292-300
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• 2009

This paper considers a robust adaptive stabilization problem for a class of uncertain nonlinear systems which include an unknown virtual control coefficient, an unknown constant parameter, and a time-varying disturbance whose bound is unknown, We propose a new estimator for an un-known virtual control coefficient and present a robust adaptive backstepping design procedure which results in a smooth state feedback control law, a new two-dimensional parameter update law, and a $C^1$ Lyapunov function which is positive definite and proper.