• Proceedings of the Computational Structural Engineering Institute Conference
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• 2004.10a
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• pp.135-142
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• 2004

Two-step identification approach for effective bridge health monitoring is proposed to alleviate the issues associated with many unknown parameters faced in the real structures and to improve the accuracy in the estimate results. It is suitable for on-line monitoring scheme, since the damage assessment is not always needed to be carried out whereas the alarming for damages is to be continuously monitored. In the first step for screening potential damaged members, damage indicator method based on modal strain energy, probabilistic neural networks and the conventional neural networks using grouping technique are used and then the conventional neural network technique is utilized for damage assessment on the screened members in the second step. The proposed methods are verified through a field test on the northern-most span of old Hannam Grand Bridge.

• Wind and Structures
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• v.7 no.3
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• pp.173-186
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• 2004

Flutter derivatives provide the basis of predicting the critical wind speed in flutter and buffeting analysis of long-span cable-supported bridges. In this paper, one popular stochastic system identification technique, covariance-driven Stochastic Subspace Identification(SSI in short), is firstly presented for estimation of the flutter derivatives of bridge decks from their random responses in turbulent flow. Secondly, wind tunnel tests of a streamlined thin plate model and a ${\Pi}$ type blunt bridge section model are conducted in turbulent flow and the flutter derivatives are determined by SSI. The flutter derivatives of the thin plate model identified by SSI are very comparable to those identified by the unifying least-square method and Theodorson's theoretical values. As to the ${\Pi}$ type section model, the effect of turbulence on aerodynamic damping seems to be somewhat notable, therefore perhaps the wind tunnel tests for flutter derivative estimation of those models with similar blunt sections should be conducted in turbulent flow.

• Ceramist
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• v.22 no.3
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• pp.269-280
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• 2019

Ceramic layered double hydroxide (LDH) nanohybrids have attracted considerable interest in biomedical science due to their unique structural feature and characteristics in biological condition. Many studies on LDH nanoparticles have been reported in diagnosis applications including magnetic resonance imaging (MRI) contrast agents in order to not only provide better imaging performance through multimodal imaging strategy, but realize therapeutic function which treat cancers in one platform. This review highlights the recent progress in MRI T₁ contrast agent, dual modal imaging system, and MRI-guided drug delivery systems ranging from synthetic method and characterization to evaluation in vitro and in vivo based on the ceramic LDH nanohybrids. Future research directions are also suggested for next-generation bio-imaging contrast agent.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2006.05a
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• pp.183-186
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• 2006

생체인식은 정보처리시스템에 있어서 네트웍 보안, 시스템 보안, 어플리케이션 보안 등에 사용되는 개인인증 및 확인을 위한 하나의 기법으로 볼 수 있으며, 개인정보를 포함한 데이터의 보호를 위해서 본인이나 승인된 사용자만이 네트웍이나 물리적 접근 등을 통하여 접근하고자 하는 것이다. 본 논문에서는 얼굴인식과 홍채인식 시스템을 융합한 다중생체인식 시스템을 구현하였으며, 다중생체인식 시스템에서 구현된 생체데이터를 안전하게 전송할 수 있는 방법으로 블록 암호 알고리듬 ARIA를 침입에 대한 보안 방법으로 제안하였다. 이에 다중생체 특징벡터를 128비트의 블록 크기를 이용하여 암호화 하였으며, 생체 특징벡터를 이용하여 128비트의 키로 사용하였다.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.226-229
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• 1989

With the increasing number of power plants in modern electric power systems, power system dynamics studies become more complex. Frequently, only some part of the power system is interesting. So it becomes necessary to reduce the size of dynamics or to introduce the dynamic equivalencing techniques. The major approach of dynamic equivalencing techniques are two: one is coherency approach, which seperates machines in groups and combines machines within each group closely swinging together into one equivalent and the other is modal approach which neglects the fast modes of external system. In this paper, a new dynamic equivalencing approach which seperates machines in coherent groups as the coherency method but doesn't predetermine the structure of the equivalent.

• Proceedings of the KIEE Conference
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• 2000.11a
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• pp.39-42
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• 2000

In stressed power system, due to the presence of increased nonlinearity and the existence of nonlinear modal interactions, there exist some limitations to the use of conventional linear system theory to identify the optimum sites for controller. This paper proposes an approach to identify the optimum sites for controller using the method of normal forms. In this paper nonlinear participation factor and coupling factor are proposed as a measures of identification of optimum sites for controller and a selection procedure is also proposed. The proposed procedure is applied to the 10-generator New England System and the KEPCO System in the year of 2010 to illustrate its capabilities.

• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1042-1045
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• 1999

This paper presents a new method for contingency selection of the transient stability. Contingency ranking in transient stability is done by estimating the change in the imaginary part of electro-mechanical oscillation mode, which represents modal synchronizing coefficient. And the change in the imaginary part is obtained by applying eigen-sensitivity theory of augmented matrix to linear system model. The Proposed algorithm was tested for New England System and compared the results with PSS/E dynamic simulation.

• International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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• v.4 no.1
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• pp.31-37
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• 2001

In this paper, an integrated damage identification system (IDIS) is proposed to locate and size damage in real structures. The application of the IDIS to real structures includes the measurement of modal responses, the construction of damage-detection models, and the implementation of measurements and models into the damage-detection process. Firstly, the theory of the damage identification method is outlined. Secondly, the schematic and each component of the IDIS are described. Finally, the practicality of the IDIS is verified from experiments on two different bridge-models, a model plate-grider and a model truss.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.533-538
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• 1991

In the design and operation of robot arms with flexible links, the equations of motion are required to exactly model the interaction between rigid motion and elastic motion and to be formulated efficiently. Thus, the flexible link is represented on the basis of the D-H rigid link representation to measure the elastic deformation. The equations of motion of robot arms, which are configured by the generalized coordinates of elastic and rigid degrees of freedom, are formulated by using F.E.M. to model complex shaped links systematically and by eliminating elastic mode of higher order that does not largely affect motion to reduce the number of elastic degree of freedom. Finally, presented is the result of simulation to flexible robotic arm whose joints are controlled by direct or PD control,

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.255-259
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• 1989

A suboptimal output feedback controller is designed and applied to a flexible rotor bearing system in order to control the unstable or lilghtly damped vibrations. The reduced order model is the truncated modal equation of the distributed parameter system obtained through the singular perturbation. The instability problem arising from the spillover effects caused by the uncontrolled high frequency modes is prevented through the constrained optimization by incorporating the spillover term into the performance index. The efficiency of the proposed method is demonstrated experimentally with a flexible rotor by using a magnetic bearing.