• Journal of the Korea Institute of Military Science and Technology
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• v.2 no.2
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• pp.251-260
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• 1999

The stiffness of joint parts in the finite element beam model are corrected by the direct comparison between the modal test and analysis model. The corrected stiffness are reviewed according to the boundary conditions of modal testing. For the improved modal test/analysis correction, more modes measured than acceleration sensors are used to make a minimal order system model. In addition, the initial F.E. model is reduced to the degrees of freedom of a minimal order system model, keeping the dynamics of the initial model. Finally, for the parametric correction of the reduced model, the submatrices are used to model the initially assumed stiffness.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.6
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• pp.487-493
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• 2001

In this paper, a new reduced-order dynamic observer method is presented. Two types of observers are pronounced, namely, the model based reduced-order dynamic observer and the Luenburger type reduced-order dynamic observer. Useful design algorithms are also provided for each structure. The essential features of the proposed observed design methods are addressed to be qualified ad effective observers. The proposed method clarifies the duality between the controller and observer designs.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.4
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• pp.280-286
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• 1987

A new method is presented for obtaining redced-order model for time-invariant systems. This method does not require the calculation of the reciprocal transformation, the alpha table, the beta-table and the alpha-beta expansion which should be calculated in Routh approximation method, hence it is computationally very attractive better than Routh approximation method, furthemore the stability of the reduced-order model is guaranted if the original system is stable. This method starts with the continued fraction espansion of auxiliary denominator polynomial give for the denominator polynomial of the reduced-order model. The coefficients of the numerator polynomial are then obtained by equating moment of the original and the reduced-order medel.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.9
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• pp.2211-2224
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• 1994

On face milling operation a new optimal cutter, which can minimize the resultant cutting forces, was designed from the cutting force model. Cutting experiments were carried out and the cutting forces of the new and conventional cutters were analyed in time and frequency domains. The resultant cutting forces were used as the objective function and cutter angles as the variables. A new optimal cutter design model which can minimize the resultant cutting forces under the constraints of variables was developed and its usefulness was proven. The cutting forces in feed direction of the newly designed cutter are reduced in comparison with those from the conventional cutter. The magnitudes of an insert frequency component of cutting force from the newly designed cutter are reduced than those from conventional cutter and the fluctuations of cutting force are also reduced.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.6
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• pp.359-365
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• 2005

This paper presents an reduced-order near-optimal controller for the congestion control of Available Bit Rate (ABR) service in Asynchronous Transfer Mode (ATM) networks. We introduce the model, of a class of ABR traffic, that can be controlled using a Explicit Rate feedback for congestion control in ATM networks. Since there are great computational complexities in the class of optimal control problem for the ABR model, the near-optimal controller via reduced-order technique is applied to this model. It is implemented by the help of weakly coupling and singular perturbation theory, and we use bilinear transformation because of its computational convenience. Since the bilinear transformation can convert discrete Riccati equation into continuous Riccati equation, the design problems of optimal congestion control can be reduced. Using weakly coupling and singular perturbation theory, the computation time of Riccati equations can be saved, moreover the real-time congestion control for ATM networks can be possible.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.194-205
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• 2009

In geotechnical engineering, the mechanical characteristics of soil, the main material of geotechnical engineering, is highly related to the confining stress. Reduced-scale physical modeling is often conducted to evaluate the performance or to verify the behavior of the geotechnical systems. However, reduced-scale physical modeling cannot replicate the behavior of the full-scale prototype because the reduced-scale causes difference of self weight stress level. Geotechnical centrifuges are commonly used for physical model tests to compensate the model for the stress level. Physical modeling techniques using centrifuge are widely adopted in most of geotechnical engineering fields these days due to its various advantages. In this paper, fundamentals of geotechnical centrifuge modeling and its application area are explained. State-of-the-art geotechnical centrifuge equipment is also described as an example of KOCED geotechnical centrifuge facility at KAIST.

• Journal of Biomedical Engineering Research
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• v.40 no.3
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• pp.81-96
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• 2019

The purpose of this study is to evaluate the effects of ultraviolet blood irradiation on the blood when a low dose of ultraviolet (UV) C is directly irradiated to the blood in a diabetic rabbit model and to evaluate the effects on treatment for diabetes. This study results indicate that the reduced body weight is increased and blood glucose levels are significantly reduced after the UBI treatment is performed when compared to those prior to the UBI treatment. In addition, $HCO_3{^-}$ levels and blood pH were elevated and lowered, respectively. When the UBI treatment is performed in a diabetic rabbit model, in this result indicate that blood glucose levels are reduced.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.5
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• pp.414-420
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• 2010

This paper presents a validation of the accuracy of a reduced order model(ROM) and the efficiency of the design optimization using a Proper Orthogonal Decomposition(POD) to transonic wing/fuselage system. Three dimensional Euler equations are solved to extrude snapshot data of the full order aerodynamic analysis, and then a set of POD basis vectors reproducing the behavior of flow around the wing/fuselage system is calculated from these snapshots. In this study, reduced order model constructed through this procedure is applied to several validation cases, and then it is confirmed that the ROM has the capability of the prediction of flow field in the space of interest. Additionally, after the design optimization of the wing/fuselage system with the ROM is performed, results of the ROM are compared with results of the design optimization using response surface model(RSM). From these, it can be confirmed that the design optimization with the ROM is more efficient than RSM.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.436-441
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• 2008

One of important factors in designing array-type MEMS resonators is obtaining a desired frequency response function (FRF) within a specific range. In this paper Krylov subspace-based model order reduction using moment-matching with non-zero expansion points is represented to calculate the FRF of array-type resonators. By matching moments at a frequency around a specific range of the array-type resonators, required FRFs can be efficiently calculated with significantly reduced systems regardless of their operating frequencies. In addition, because of the characteristics of moment-matching method, a minimal order of reduced system with a specified accuracy can be determined through an error indicator using successive reduced models, which is very useful to automate the order reduction process and FRF calculation for structural optimization iterations.

• Journal of the Korean Geotechnical Society
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• v.21 no.3
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• pp.65-77
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• 2005

This paper investigates the failure mechanism of geosynthetic-reinforced segmental retaining walls with tiered configuration using reduced-scale model tests. The reduced scale model test set-up was established to simulate a 5 m high full-scale wall. The geometry and material properties used in the model test were determined based on the Similitude Laws. The wall failures in the model tests were successfully generated by their self weight without any surface loading and analyzed examining the digital video recordings. The failure mechanisms was examined with respect to the various offsets between the lower and upper teres and the reinforcement length. Based on the results the appropriateness of the current design guideline was discussed.