• Journal of Mechanical Science and Technology
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• v.14 no.3
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• pp.306-313
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• 2000

The homogenization method and the density function method are common approaches to evaluate the equivalent material properties for design cells composed of matter and void. In this research, using a new topology optimization method based on the homogenized material with a penalty factor and the chessboard prevention strategy, we obtain the optimal layout of a structure for the natural frequency of a designated mode. The volume fraction of nodes of each finite element is chosen as the design variable and a total material usage constraint is imposed. In this paper, the subspace method is used to evaluate the eigenvalue and its corresponding eigenvector of the structure for the designated mode and the recursive quadratic programming algorithm, PLBA algorithm, is used to solve the topology optimization problem.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.183-186
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• 1996

The relational database management systems sometimes require extremely long and complicated queries for a certain retreval. In this case, recursive retirevals are more efficient approach than the usual queries. Many researchers have tried to incorporate semantics in the traditional relational models using artificial intelligence techniques. This new concept becomes a deductive database and sometimes it is also called as a logic programming. However, the designer of a deductive database did not overcome the short of relational database. In this paper, we propose a new way of designing queries for the deductive database. We also provide relations for recursive retrieval in the deductive database. These approaches are applied for the material requirement planning.

• Journal of Biomedical Engineering Research
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• v.26 no.2
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• pp.87-93
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• 2005

A new method for real-time estimating left ventricular relaxation time constant (T) from the left ventricular (LV) pressure waveform, based on the isovolumic relaxation model, is proposed. The presented method uses a recursive least squares (RLS) algorithm to accomplish real-time estimation. A new criterion to detect the end-point of the isovolumic relaxation period (IRP) for the estimation of T is also introduced, which is based on the pattern analysis of mean square errors between the original and reconstructed pressure waveforms. We have verified the performance of the new method in over 4,600 beats obtained from 70 patients. The results demonstrate that the proposed method provides more stable and reliable estimation of τ than the conventional 'off-line' methods.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.9
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• pp.1639-1645
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• 2011

A technique to allocate responsibilities among the interested parties in electric power system with harmonic voltage distortion at the point of common coupling (PCC) has been presented. The recursive least-squares technique has been used to estimate the parameters of the Thevenin equivalent load model. The validity of the technique has been verified using a simulation which considered the voltage waveform distortion at the PCC between the utility and two industrial consumers. With the estimated data from the measured voltage and current waveform at the PCC, the individual contributions to the distortion of voltage waveform at an interested harmonic frequency have been calculated and could provide a flexible solution to identify the source of harmonic pollution in distribution systems.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.11
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• pp.1536-1541
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• 2018

For effective electricity consumption in urban railway station such as peak load shaving, it is important to know each electrical load pattern by various usage. The total electricity consumption in the urban railway substation is already measured in Korea, but the electricity consumption for each usage is not measured. The author proposed the deep learning method to estimate the electrical load pattern for each usage in the urban railway substation with public data such as weather data. GRU (gated recurrent unit), a variation on the LSTM (long short-term memory), was used, which aims to solve the vanishing gradient problem of standard a RNN (recursive neural networks). The optimal model was found and the estimation results with that were assessed.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.8 no.2
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• pp.75-86
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• 2004

In this study, a recursive algorithm for generating the equations of motion of a chain of rigid rods is presented. The methods rests upon the idea of replacing the rigid body by a dynamically equivalent constrained system of particles. The concepts of linear and angular momentums are used to generate the rigid body equations of motion without either introducing any rotational coordinates or the corresponding transformation matrices. For open-chain, the equations of motion are generated recursively along the serial chains. For closed-chain, the system is transformed to open-chain by cutting suitable kinematic joints with the addition of cut-joints kinematic constraints. An example of a closed-chain of rigid rods is chosen to demonstrate the generality and simplicity of the proposed method.

• Structural Engineering and Mechanics
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• v.27 no.5
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• pp.527-540
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• 2007

The modal controller of single-input system cannot stabilize the defective system with positive real part of repeated eigenvalues, because some of the generalized modes are uncontrollable. In order to stabilize the uncontrollable modes with positive real part of eigenvalues, the multi-input system should be introduced. This paper presents a recursive procedure for designing the feedback controller of the multi-input system with defective repeated eigenvalues. For a nearly defective system, we first transform it into a defective one, and apply the same method to manage. The proposed methods are based on the modal coordinate equations, to avoid the tedious mathematic manipulation. As an application of the presented procedure, two numerical examples are given at end of the paper.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.18 no.3
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• pp.21-26
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• 2010

This paper deals with the precise parameter estimation of an air vehicle without a priori information. First, Recursive Least Squares technique, which is an equation error method and does not require any a priori information, is applied and then the extended Kalman filter is used to tune parameters more precisely. To show the performance, a nonlinear longitudinal missile model is simulated and the parameters are estimated. The results show that this consecutive application of the techniques gives a very good estimation performance.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07b
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• pp.151-153
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• 2005

오늘날 HTML을 대체하기 위해 등장한 XML은 디지털 정보교환 형식의 표준으로 자리 잡은 후 XML 문서를 데이터베이스에 저장하고 원하는 정보를 효율적으로 질의한 후 결과를 출력하는 연구가 활발히 진행되고 있다. 본 논문에서는 XML 문서를 미리 설계되어진 Analyzer를 이용해서 관계형 테이블에 저장한 후 사용자가 XQuery를 사용하여 질의를 한다. 변환기에 의해서 SQL로 데이터베이스에 질의를 하게 되고 그 결과는 테이블에서 다시 XML 형태로 재생성하여 사용자는 XML 형태의 결과를 볼 수 있다. 본 논문에서는 XQuery로 질의한 결과를 다시 XML로 재생성하는 기법에 대한 설명과 관련 테이블의 구조와 구현 과정을 비롯하여 접기서 제시한 재생성 기법을 recursive function으로 구현한 경우와 반복문으로 구현한 경우를 테스트하여 recursive function으로 구현한 경우가 반복문으로 구현한 경우보다 재생성하는 시간이 빠르다는 것을 확인하고 보다 효율적이라는 결론을 제시한다.

• Journal of information and communication convergence engineering
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• v.6 no.3
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• pp.310-314
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• 2008

This paper proposes a very novel method which makes it possible that state feedback controller can be designed for unknown dynamic system with measurable states. This novel method uses the support vector machines (SVM) with its function approximation property. It works together with RLS (Recursive least-squares) algorithm. The RLS algorithm is used for the identification of input-output relationship. A virtual state space representation is derived from the relationship and the SVM makes the relationship between actual states and virtual states. A state feedback controller can be designed based on the virtual system and the SVM makes the controller with actual states. The results of this paper can give many opportunities that the state feedback control can be applied for unknown dynamic systems.