• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.4 no.4
• /
• pp.895-899
• /
• 2000

A method of measuring Q of a two port cavity by scattering parameters is proposed. The scattering parameters of a two port cavity resonator are derived by a lumped equivalent circuit model as a function of cavity parameters, including the cavity Q. These can be also obtained by direct measurement with a modern network analyzer, The results show good agreement with those from other well-known methods. This two port measurement can provide additional information such as the coupled power ratio, which is one of the important parameters for the beam accelerating cavities.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.45 no.7
• /
• pp.17-21
• /
• 2008

As with the binary pseudo-random sequences q-ary m-sequences possess very good properties which make them useful in many applications. So we construct a class of Jacket matrices by applying additive characters of the finite field $F_q$ to entries of all shifts of q-ary m-sequence. In this paper, we generalize a method of obtaining conventional Hadamard matrices from binary PN-sequences. By this way we propose Jacket matrix construction based on q-ary M-sequences.

• Journal of Broadcast Engineering
• /
• v.21 no.1
• /
• pp.60-65
• /
• 2016

This paper introduces the non-local means (NLM) algorithm for image denoising, and also introduces an improved algorithm which is based on the principal component analysis (PCA). To do the PCA, a covariance matrix of a given image should be evaluated first. If we let the size of neighborhood patches of the NLM S × S², and let the number of pixels Q, a matrix multiplication of the size S² × Q is required to compute a covariance matrix. According to the characteristic of images, such computation is inefficient. Therefore, this paper proposes an efficient method to compute the covariance matrix by sampling the pixels. After sampling, the covariance matrix can be computed with matrices of the size S² × floor (Width/l) × (Height/l).

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2015.07a
• /
• pp.205-207
• /
• 2015

본 논문에서는 먼저 주성분 분석 (Principal components analysis, PCA) 을 활용한 Non-local means (NLM) 을 소개하고, 주성분 분석을 하기 위해 필수적인 공분산 행렬 계산을 효율적으로 하는 방법을 제안한다. NLM 에서의 Neighborhood patch 의 크기를 $S{\times}S=S^2$, 이미지 전체의 픽셀 수를 ${\mathcal{Q}}$ 일 때 공분한 행렬을 계산 하기 위해서는 $S^2{\times}{\mathcal{Q}}$ 크기를 가지는 행렬간의 곱 연산이 필요하다. 결론적으로 본 논문에서는 이 행렬의 크기를 줄임으로써 PSNR (Peak signal-to-noise ratio) 의 손실 없이 NLM 의 복잡도를 줄일 수 있음을 보여준다.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.32 no.1
• /
• pp.45-54
• /
• 2019

The damage detection method using the extended Kalman filter(EKF) technique has been continuously used since EKF can estimation the responses of the damaged building structure and the stiffness of the structure. However, in the use of EKF, the requirement of setting the initial paramters P, Q, and R has caused the divergence and instability of the state vector, and various researches have been conducted to determine theses parameters. In this paper, adaptive extended Kalman filter(AEKF) method is proposed to solve the problem of setting the values of P, Q, and R, which are important parameters determining the convergence performance of the EKF state vector. By using the AEKF method proposed in this study, the P, Q, and R parameters are updated every k steps. The proposed algorithm is applied for the estimation of stiffness and the damage detection of 3-DOF problem. Based of the verification, it can be found that the selection process for the values of P, Q, and R can improve the convergence performance of EKF.

• Journal of Institute of Control, Robotics and Systems
• /
• v.4 no.6
• /
• pp.707-712
• /
• 1998

본 논문에서는 선형 시불변 시스템에 대해 상태되먹임을 이용한 폐루프계의 지정된 영역내의 극배치법을 제안한다. 본 제안된 기법은 해밀톤 행렬의 하중행렬 Q의 설정에 의해 지정된 영역 (α중심, γ반경)내에 극배치가 가능함을 보인다. 먼저, Gershgorin의 이론을 적용하기 위해 해밀톤 행렬을 등가 변환시킨 후 행렬의 각 계수를 α와 γ의 관계를 이용하여 유도한다. 위의 관계를 만족하는 해밀톤 행렬의 각 하중행렬과 변환행렬을 이용하여 폐루프계의 상태되먹임 제어칙을 구한다. 또한 본 기법은 해밀톤 행렬과 최적제어와의 관계를 지니고 있으므로 얻어진 폐루프계는 최적제어법에서와 동일한 강인함을 가지게 된다. 끝으로 예제를 통하여 지정된 영역내의 극배치가 이루어짐을 보인다.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.22 no.4
• /
• pp.602-610
• /
• 2018

The model predictive control is an effective method to optimize the current control input that predicts the current control state and the future error using the predictive model of the control system when the reference trajectory is known. Since the control input can not have a physically infinitely large value, a predictive controller design with constraints should be considered. In addition, the reference model $A_r$ and the weight matrices Q, R that determine the control performance of the predictive controller are not optimized as arbitrarily designated should be considered in the controller design. In this study, we construct a predictive controller of a mobile robot by transforming it into a quadratic programming problem with constraints, The control performance of the mobile robot can be improved by optimizing the control parameters of the predictive controller that determines the control performance of the mobile robot using genetic algorithm. Through the computer simulation, the superiority of the proposed method is confirmed by comparing with the existing method.

• Review of KIISC
• /
• v.2 no.4
• /
• pp.104-109
• /
• 1992

스위치 이론이나 디지탈 공학$^{2)}$, 정보보호학$^{6.8)}$등의 분야에서 자주 사용되는 많은 함수들은 유한체 GF$(q)^n$에서 GF(q)의 값을 취하는 함수들이다. 특히 q=2인 경우에 함수 f는 쉽게 진리표에 의해 표현된다. 본 글에서는 유한체 위에서 성립하는 행렬 구조를 갖는 대수적 표준형식 변환에 대하여 알아보고, 변환의 계산을 점화적으로 이행해보며, 난수함수의 복잡도에 관한 확률분포를 살펴본다. 대수적 표준형식은 함수의 비선형 위수나 복잡도에 관한 판단에 유용하게 응용할 수 있다.

• Journal of the Korea Society of Computer and Information
• /
• v.11 no.3
• /
• pp.141-149
• /
• 2006

In this paper, we introduce an improved algorithm for computing matrix triple product that commonly arises in primal-dual optimization method. In computing $P=AHA^{t}$, we devise a single pass algorithm that exploits the block diagonal structure of the matrix H. This one-phase scheme requires fewer floating point operations and roughly half the memory of the generic two-phase algorithm, where the product is computed in two steps, computing first $Q=HA^{t}$ and then P=AQ. The one-phase scheme achieved speed-up of 2.04 on Intel Itanium II platform over the two-phase scheme. Based on memory latency and modeled cache miss rates, the performance improvement was evaluated through performance modeling. Our research has impact on performance tuning study of complex sparse matrix operations, while most of the previous work focused on performance tuning of basic operations.

• The Transactions of the Korea Information Processing Society
• /
• v.3 no.2
• /
• pp.359-368
• /
• 1996

This paper introduces PGD(Preprocessed Givens Downdating)and PHD(Preprocessed Hyperbolic Downdating) algorithms, wherein a multiple-row observation matrix $Z^T$ is factorized into a partial Cholesky factor Rz, such that $Z^T$ = $Q_zR_z, Q_zQ^T_z=I$, and then Rz is recursively downdated by using GD(Givens Downdating)and HD(Hyperbolic Dondating), respectively. Time complexities of PGD and PHD algorithms are $pn^2$ ＋ $5n^3/6$ 및 $pn^2$＋$n^3/3$ flops, respectively, if p$\geq$n, while those of the existing GD and HD are known to be $5pn^2/2$ and $2pn^2$ flops,, respectively. This concludes that the factorization of observation matrices, which we call preprocessing, would improve the overall performance of the downdating process. Benchmarks on the Sun SPARC/2 system also show that preprocessing would shorten the required downdating times compared to those of downdatings without preprocessing. Furthermore, benchmarks also show that PHD provides better performance than PGD.