• Journal of the Korean Chemical Society
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• v.52 no.3
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• pp.328-337
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• 2008

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.619-623
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• 1993

In this paper, a neural network is appled to design a lateral autopilot for airplanes. Linearized lateral dynamics is used in training the neural network controller and verifying the performance as well. To train the neural network, back propagation algorithm is used. In this training, no information about the dynamics to be controlled except sign and rough magnitude of control derivatives is needed. It is shown by computer simulations that the performance and stability margin are satisfactory.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10a
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• pp.451-456
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• 1990

We treat the problem of the robust tracking of a class of nonlinear systems which can be asymptotically decoupled in approximate sense by state variable feedback. A nonlinear control law is derived such that the tracking error in the closed loop system is uniformly bounded and tends to a certain small neighborhood of the origin. Simulation results show that simultaneous lateral and longitudinal maneuvers in airplane can be accurately performed in spite of uncertainty in stability derivatives.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.10
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• pp.1467-1474
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• 2004

In this study, a new damage identification method for beam-like structures with a fatigue crack is proposed. which does not require comparative measurement on an intact structure but require several measurements at different level of excitation forces on the cracked structure. The idea comes from the fact that dynamic behavior of a structure with a fatigue crack changes with the level of the excitation force. The 2$^{nd}$ spatial derivatives of frequency response functions along the longitudinal direction of a beam are used as the sensitive indicator of crack existence. Then, weighting function is employed in the averaging process in frequency domain to account for the modal participation of the differences between the dynamic behavior of a beam with a fatigue crack at the low excitation and one at the high excitation. Subsequently, a damage index is defined such that the location and level of the crack may be identified. It is shown from the analysis of vibration measurements in this study that comparison of frequency response characteristics of a beam with a single fatigue crack at different level of excitation forces enables an effective detection of the crack.

• Wind and Structures
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• v.5 no.2_3_4
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• pp.277-290
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• 2002

A two dimensional discrete vortex method (DIVEX) has been developed at the Department of Aerospace Engineering, University of Glasgow, to predict unsteady and incompressible flow fields around closed bodies. The basis of the method is the discretisation of the vorticity field, rather than the velocity field, into a series of vortex particles that are free to move in the flow field that the particles collectively induce. This paper gives a brief description of the numerical implementation of DIVEX and presents the results of calculations on a recent suspension bridge deck section. The results from both the static and flutter analysis of the main deck in isolation are in good agreement with experimental data. A brief study of the effect of flow control vanes on the aeroelastic stability of the bridge is also presented and the results confirm previous analytical and experimental studies. The aeroelastic study is carried out firstly using aerodynamic derivatives extracted from the DIVEX simulations. These results are then assessed further by presenting results from full time-dependent aeroelastic solutions for the original deck and one of the vane cases. In general, the results show good qualitative and quantitative agreement with results from experimental data and demonstrate that DIVEX is a useful design tool in the field of wind engineering.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2018.10a
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• pp.122-122
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• 2018

We previously showed that the root extract of Paeonia lactiflora might have anti-inflammatory effects. Paeoniflorin (PF) has been identified as one of the main bioactive components of Paeonia lactiflora, however its role has been well characterized. In this study, we tested whether PF and its derivatives, which is removed the hydroxy group from PF, might have anti-inflammatory effects. In the Nitric Oxide assay, PF and Paeoniflorin's derivative (PFD) showed 55% and 56% more anti-inflammatory effect, compared to LPS control, respectively at 250ug/ml. To further confirm, we examined the effect of PF on tyrosine phosphorylation of Erk MAP Kinase. It is well established that tyrosine phosphorylation of Erk MAP Kinase is related to NF-kB mediated inflammation pathway. We therefore examined whther PF and PFD might regulate Erk activity. PF and PFD showed 35% and 22% less tyrosine phosphorylation compared to Paeonia lactiflora Red Charm extract control, respectively at 500ug/ml. Taken together, these results suggest that PF and PFD may play a role in anti-inflammatory effects in the root extract of Paeonia lactiflora. This study will provide the basis to develop a platform for the inflammation-mediated diseases therapeutics in the near future.

• Wind and Structures
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• v.4 no.4
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• pp.333-352
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• 2001

A two dimensional discrete vortex method (DIVEX) has been developed to predict unsteady and incompressible flow fields around closed bodies. The basis of the method is the discretisation of the vorticity field, rather than the velocity field, into a series of vortex particles that are free to move in the flow field that the particles collectively induce. This paper gives a brief description of the numerical implementation of DIVEX and presents the results of calculations on a recent suspension bridge deck section. The predictions for the static section demonstrate that the method captures the character of the flow field at different angles of incidence. In addition, flutter derivatives are obtained from simulations of the flow field around the section undergoing vertical and torsional oscillatory motion. The subsequent predictions of the critical flutter velocity compare well with those from both experiment and other computations. A brief study of the effect of flow control vanes on the aeroelastic stability of the bridge is also presented and the results from DIVEX are shown to be in accordance with previous analytical and experimental studies. In conclusion, the results indicate that DIVEX is a very useful design tool in the field of wind engineering.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.941-946
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• 2005

In this paper an active random noise control using adaptive learning rate neural networks is presented. The adaptive learning rate strategy increases the learning rate by a small constant if the current partial derivative of the objective function with respect to the weight and the exponential average of the previous derivatives have the same sign, otherwise the learning rate is decreased by a proportion of its value. The use of an adaptive learning rate attempts to keep the learning step size as large as possible without leading to oscillation. It is expected that a cost function minimize rapidly and training time is decreased. Numerical simulations and experiments of active random noise control with the transfer function of the error path will be performed, to validate the convergence properties of the adaptive learning rate Neural Networks. Control results show that adaptive learning rate Neural Networks control structure can outperform linear controllers and conventional neural network controller for the active random noise control.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.216-217
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• 2005

This paper presents an integrated navagation control concept for underwater vehicles under high speed navigation circumstance. First of all, in order to control an underwater vehicle with respect to automatic navigation, an integrated navigation control method is suggested in view of synchronous control for course keeping, diving and depth control. An exact nonlinear model equation with six-degree-of-freedom is derived for control algorithm. To identify various hydrodynamic coefficients of the equation, an experimental approach is introduced and results are demonstrated for MANTA type model.

• Structural Engineering and Mechanics
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• v.46 no.4
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• pp.549-569
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• 2013

A passive control using flaps will be an alternative solution for flutter stability and buffeting response of a long suspension bridge. This method not only enables a lightweight economic stiffening girder without an additional stiffness for aerodynamic stability but also avoid the problems from the malfunctions of control systems and energy supply system of an active control by winglets and flaps. A time domain approach for predicting the coupled flutter and buffeting response of bridge deck with flaps is investigated. First, the flutter derivatives of bridge deck and flaps are found by experiment. Next, the derivation of time domain model of self-excited forces and control forces of sectional model is reported by using the rational function approximation. Finally, the effectiveness of passive flap control is investigated by the numerical simulation. The results show that the passive control by using flaps can increase the flutter speed and decrease the buffeting response. The experiment results are matched with numerical ones.