• 한국정보통신학회논문지
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• 제11권3호
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• pp.491-499
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• 2007

본 논문에서는 Reed-Muller 전개식에 의한 3치 논리 회로를 설계하는 한 가지 방법을 제시하였다. 제시된 3치 논리 회로의 설계 방법은 Reed-Muller 전개식의 계수에 대하여 모든 변수의 차수를 검사하여 RME 모듈(Reed-Muller Expansions module)의 수를 최소화하는 최적의 제어 입력 변수의 순서를 결정한다. 최적의 제어 입력 변수의 순서는 회로 비용 행렬의 계산에 사용되며, 이 회로 비용 행렬의 계산 결과를 이용하여 Reed-Muller 전개식에 의한 RME 모듈의 나무 구조의 3치 논리 회로를 설계한다. 제시된 방법은 최적 제어 입력 변수를 찾는데 유일하게 단위시간 내에 수행되며, 컴퓨터 프로그램이 가능하고, 프로그래밍 수행 시간이 $3^n$이다.

• Smart Structures and Systems
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• 제2권2호
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• pp.127-140
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• 2006

In this study, a wavelet-based covariance-driven system identification technique is proposed for damage assessment of structures under ambient excitation. Assuming the ambient excitation to be a white-noise process, the covariance computation is shown to be able to separate the effect of random excitation from the response measurement. Wavelet transform (WT) is then used to convert the covariance response in the time domain to the WT magnitude plot in the time-scale plane. The wavelet coefficients along the curves where energy concentrated are extracted and used to estimate the modal properties of the structure. These modal property estimations lead to the calculation of the stiffness matrix when either the spectral density of the random loading or the mass matrix is given. The predicted stiffness matrix hence provides a direct assessment on the possible location and severity of damage which results in stiffness alteration. To demonstrate the proposed wavelet-based damage assessment technique, a numerical example on a 3 degree-of-freedom (DOF) system and an experimental study on a three-story building model, which are all under a broad-band excitation, are presented. Both numerical and experimental results illustrate that the proposed technique can provide an accurate assessment on the damage location. It is however noted that the assessment of damage severity is not as accurate, which might be due to the errors associated with the mode shape estimations as well as the assumption of proportional damping adopted in the formulation.

• 대한토목학회논문집
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• 제29권4B호
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• pp.377-384
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• 2009

다중 계단으로 근사한 사주지형 위를 지나는 선형 파랑전파에 대한 고유함수 전개법에서 크기가 큰 행렬을 풀 때 계산시간을 상당히 단축하기 위하여 분할행렬법을 사용하여 반사율을 계산하였다. 본 모형에 10개의 억류파를 사용하여 현재까지 가장 정밀한 수치해를 구하였고 구한 반사율의 거동은 몇 경우에서 기존 결과와 다름을 보였다. 크기가 큰 행렬을 풀 때 본 분할행렬법의 계산시간과 기억용량은 여전히 커서 효율적인 방법에 대한 개발이 요구된다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1996년도 춘계학술대회논문집; 부산수산대학교, 10 May 1996
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• pp.253-256
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• 1996

Stiffened panels are very frequently used for body structures of automobiles, air-crafts, submarines, etc., to suppress the vibration level. Swaging technique is the modification of the configuration of panel itself, and this is prefered to rib-like stiffeners because it does not change the total weight of structure. In this paper, the transmissibility of vibratory power through swage is investigated, where the swage is modeled as an incomplete circular ring, utilizing the well-known transfer matrix method. The power transmission and reflection coefficients of swaged panel are estimated and compared with experimental results.

• 한국염색가공학회지
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• 제18권5호
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• pp.88-93
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• 2006

A data compression system has been developed by combining adaptive wavelets and optimization technique. The adaptive wavelets were made by optimizing the coefficients of the wavelet matrix. The optimization procedure has been performed by criteria of minimizing the reconstruction error. The resulting adaptive basis outperformed such conventional basis as Daubechies-5 by 5-10%. It was also shown that the yarn density profiles could be compressed by over 95% without a significant loss of information.

• Journal of applied mathematics & informatics
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• 제26권3_4호
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• pp.751-755
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• 2008

Formanek([2]) proved that $M_n(K)$, the matrix algebra has a nontrivial central polynomial when char K = 0. Also Razmyslov([3]) showed the same result using the essential weak identity. In this article we explicitly compute Formanek's central polynomial for $M_2(\mathbb{C})$ and $M_3(\mathbb{C})$ and classify the coefficients of the central polynomial.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 B
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• pp.727-729
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• 1992

In this study, the piezoelectric composites with 1-3 connectivity have been studied. A piezoelectric ceramics PZT prepared by Flux method is used as a filler in a epoxy Eccogel polymer matrix. The piezoelectric coefficients were increased as PZT volume% increases, and resonance frequency was moved to lower frequency as the sample thickness increased. The acoustic matching impedance with water is lowered than single phase PZT ceramics.

• 한국생산제조학회지
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• 제22권6호
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• pp.950-956
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• 2013

This paper describes a sensitivity-coefficient-based iterative method for detecting cracks in a structure. The sensitivity coefficients of a cracked structure are obtained by changing its eigenvectors. The proposed method is applied to a cracked cantilever. The crack is modeled as a rotational stiffness. The predicted cracks are in good agreement with those from a structural reanalysis of the cracked structure.

• International Journal of Safety
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• 제3권1호
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• pp.1-5
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• 2004

This study discusses frequency analysis based on autoregressive (AR) time series model, and the characterization of surface quality in orthogonal cutting of a fiber-matrix composite materials. A sparsely distributed idealized composite material, namely a glass reinforced polyester (GFRP) was used as workpiece. Analysis method employs a force sensor and the signals from the sensor are processed using AR time series model. The experimental correlations between the fiber pull-out and AR model coefficients are then established.

• 한국산업안전학회:학술대회논문집
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• 한국안전학회 2000년도 춘계 학술논문발표회 논문집
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• pp.52-57
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• 2000

This paper discusses frequency analysis based on frequency spectrum in orthogonal cutting of fiber-matrix composite materials. A glass reinforced polyester (GFRP) was used as workpiece. Analysis method employs a force sensor and the signals from the sensor are processed using a fast Fourier transform (FFT) technique. The experimental correlation between the different chip formation mechanisms and model coefficients are then established. (omitted)