• Journal of the Korean Society for Precision Engineering
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• v.14 no.5
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• pp.92-99
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• 1997

A model reference adaptive control(MRAC) theory is very useful for controlling a plant of which the parameters are unknown or vary during operation usint only input-output signal of plant. In this study, 2' nd order discreter time MRAC controller is designed for an electrohydraulic position control system which is represented with nonlinear mathematical model and the least square method is adopted for the para-meter adjustment law. This control algorthm is applied to the position control of electrohydraulic servosystem through computer simulation and the effect of the change of load, sampling time upon the performance following reference model and upon the performance of estimating plant parameters are examined.

• Journal of the Korea Convergence Society
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• v.4 no.3
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• pp.43-50
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• 2013

This paper presents a model predictive control (MPC) based on a neural network (NN) model for air/fuel ration (AFR) control of automotive engines. The novelty of the paper is that the severe nonlinearity of the engine dynamics are modelled by a NN to a high precision, and adaptation of the NN model can cope with system uncertainty and time varying effects. A single dimensional optimization algorithm is used in the paper to speed up the optimization so that it can be implemented to the engine fast dynamics. Simulations on a widely used mean value engine model (MVEM) demonstrate effectiveness of the developed method.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.2
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• pp.121-126
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• 2000

In the fast sampling limit the delta operator model tends to the analog system model. This fundamental property of the delta operator model unifies continuous and discrete time control system. In this paper we study robust linear optimal model following servo system in the presence of disturbances and parameter perturbations. A technique to directly design the generalized differential operator based unified control system that covers both differential operator based continuous time and delta operator based discrete time case is presented. The quadratic criterion function for a linear system is used to design the robust unified servo control system The characteristics of the proposed servo system are analysed and simulated to verify the robustness.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.7
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• pp.1411-1417
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• 2009

In this paper, we consider the design of $H_{\infty}$ control of linear discrete-time systems having no mathematical model. The basic approach is to use Q-learning which is a reinforcement learning method based on actor-critic structure. The model-free control design is to use not the mathematical model of the system but the informations on states and inputs. As a result, the derived iterative algorithm is expressed as linear matrix inequalities(LMI) of measured data from system states and inputs. It is shown that, for a sufficiently rich enough disturbance, this algorithm converges to the standard $H_{\infty}$ control solution obtained using the exact system model. A simple numerical example is given to show the usefulness of our result on practical application.

• Journal of the Ergonomics Society of Korea
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• v.18 no.3
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• pp.141-152
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• 1999

In this paper, We performed the human body dynamic modelling for the realistic animation based on the dynamical behavior of human body, and designed controller for the effective control of complicate human dynamic model. The human body was simplified as a rigid body which consists of 18 actuated degrees of freedom for the real time computation. Complex human kinematic mechanism was regarded as a composition of 6 serial kinematic chains : left arm, right arm, support leg, free leg, body, and head. Based on the this kinematic analysis, dynamic model of human body was determined using Newton-Euler formulation recursively. The balance controller was designed in order to control the nonlinear dynamics model of human body. The effectiveness of designed controller was examined by the graphical simulation of human walking motion. The simulation results were compared with the model base control results. And it was demonstrated that, the balance controller showed better performance in mimicking the dynamic motion of human walking.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.4 s.181
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• pp.44-51
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• 2006

This paper addresses sliding mode control of the anti-lock braking system (ABS) with a disturbance observer for model uncertainties such as vehicle parameter variation, un-modeled dynamics, and external disturbances. By using a nominal vehicle model, a sliding mode controller is designed to achieve a desired wheel slip ratio for ABS control. To compensate the model uncertainties, a disturbance observer is introduced with the help of a transfer function of a hydraulic brake dynamics. A proposed sliding mode controller with a disturbance observer is evaluated through simulations for model uncertainties. The simulation results show that the disturbance observer can enhance performances of sliding mode control for ABS.

• International Journal of Aeronautical and Space Sciences
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• v.16 no.1
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• pp.64-76
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• 2015

This paper suggests applying pseudospectral model predictive method for exo-atmospheric guidance. The method is a fusion of pseudospectral law and model predictive control, in which a two point boundary value problem is formulated using model predictive approach and solved by applying pseudospectral law. In this work, the method is applied to exo-atmospheric guidance with specific target requirement. The existing exo-atmospheric guidance methods suffice general requirements for guidance, but cannot ensure specific target constraints; whereas, the presented method is able to do so. The proposed guidance law is assessed through simulation of perturbed cases, and the tests suggest that the method is able to operate semi-autonomously under control and thrust vector perturbations.

• Journal of Internet Computing and Services
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• v.7 no.1
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• pp.1-16
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• 2006

The vulnerability of privacy in the Identity Management System (IMS) is the most pressing concern of ordinary users. Uncertainty about privacy keeps many users away from utilization of IMS. Therefore, this paper proposes an access-control oriented privacy model for IMS. The proposed model protects privacy using access control techniques with privacy policies in a single circle of trust. We address characteristics of the components of for the proposed model and describe access control procedures. After that, we show the architecture of privacy enforcement and XML-based schema for privacy policies.

• The Journal of Internal Korean Medicine
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• v.19 no.1
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• pp.114-133
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• 1998

In order to investigate the effects of Alcohol-Steamed Rhei Rhizoma and Row Rhei Rhizoma on varied extract time in both endotoxin-induced blood stasis model(hereafter Endotoxin Model) and hydrocortisone acetate-induced blood stasis model (hereafter HA Model), Half of rats were treated with endotoxin(0.4mg/kg, single Ⅳ, into caudal vein) for Endotoxin Model. Thereafter, they were orally administrated water extract of Alcohol-Steamed Rhei Rhizoma or Row Rhei Rhizoma, which were boiled during 30, 60, 120 minute, respectively. Finally, the number of platelet, fibrinogen, prothrombin time, hematocrit, the number of RBC and WBC were measured after sacrifice. The remainder rats were treated with hydrocortisone acetate(10mg/kg, daily IM for 7 days into the muscular rump) for HA significantly decreased. Together, they were orally administrated for 7 days water extract of Alcohol-Steamed Rhei Rhizoma or Row Rhei Rhizoma that were boiled above methods Finally, the number of platelet, fibrinogen, prothrombin time, hematocrit, the number of RBC and WBC were measured after sacrifice. The results were summarized as follows : 1. The number of platelet was significantly increased in boiled water extract for 30 min of Row Rhei Rhizoma group as compared with that of control group in Endotoxin Model. 2. Fibrinogen level was significantly increased in all administration groups as compared with that of control group in Endotoxin Model. It was significantly increased in all administration groups except boiled water extract for 30 min of Alcohol-Steamed Rhei Rhizoma group as compared with that of control group in HA Model. 3. Prothrombin time was significantly shortened in boiled water extract for 60 min of Alcohol-Steamed Rhei Rhizoma group and boiled water extract for 120 min of Alcohol-Steamed Rhei Rhizoma group as compared with that of control group in Endotoxin Model It was significantly shortened all administration groups as compared with that of control group in HA Model. 4 Hematocrit was significantly increased in all administered groups except boiled water extract for 60 min of Alcohol-Steamed Rhei Rhizoma group and boiled water extract for 30 min of Row Rhei Rhizoma group as compared with that of control group in Endotoxin Model. It was significantly increased in all administration groups as compared with that of control group in HA Model. 5. The number of RBC was significantly decreased in boiled water extract for 60 min of Alcohol-Steamed Rhei Rhizoma group, boiled water extract for 120 min of Alcohol -Steamed Rhei Rhizoma group and boiled water extract for 30 min of Row Rhei Rhizoma administered group in Endotoxin Model. It was significantly increased boiled water extract for 30 min of Row Rhei Rhizoma group and boiled water extract for 60 min of Row Rhei Rhizoma group in HA Model as compared with data of control group. 6 The number of WBC was significantly decreased in all administered groups except boiled water extract for 30 min of Alcohol-Steamed Rhei Rhizoma group and boiled water extract for 60 min of Alcohol-Steamed Rhei Rhizoma group as compared with that of control group in HA Model.

• Journal of Information Processing Systems
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• v.2 no.1
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• pp.28-33
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• 2006

The initial research of Task Computing in the ubiquitous computing (UbiComp) environment revealed the need for access control of services. Context-awareness of service requests in ubiquitous computing necessitates a well-designed model to enable effective and adaptive invocation. However, nowadays little work is being undertaken on service access control under the UbiComp environment, which makes the exposed service suffer from the problem of ill-use. One of the research focuses is how to handle the access to the resources over the network. Policy-Based Access Control is an access control method. It adopts a security policy to evaluate requests for resources but has a light-weight combination of the resources. Motivated by the problem above, we propose a universal model and an algorithm to enhance service access control in UbiComp. We detail the architecture of the model and present the access control implementation.