• Investigative Magnetic Resonance Imaging
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• 제11권2호
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• pp.110-118
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• 2007

목적: 확산텐서자기공명영상(DT-MRI: Diffusion Tensor Image)을 이용하여 확산의 주축을 구성하는 세 성분에 대한 고유치 (eigefvalue)의 영상을 구현해 보고자 하였다. 대상 및 방법: 고유치 영상을 구현하기 위해서 3.0 테슬러 MRI(Magnetic Resonance Imaging)를 이용하여 확산텐서영상을 얻었으며, Moore-Penrose pseudo-inverse 방법과 SVD(single value decomposition) 방법을 이용하여 확산 주축을 계산하였다. 이 과정을 픽셀단위로 반복적으로 계산하여 새로운 확산 주축 영상들을 만들었으며, 이 확산 주축 영상들과 분할 비등방성 영상의 관계를 조사하였다. 결과: 확산텐서영상 기법으로 얻어진 확산텐서영상을 이용하여, 세 방향의 확산 주축에 대한 고유치 영상을 구성하였으며, 고유치 영상들과 분할 비등방성 영상을 함께 분석함으로써, 뇌의 해부학적 구조물에 따른 분할 비등방성 값의 차이를 확인할 수 있었다. 또한, 확산 주축에 대한 고유치의 변화에 대한 컴퓨터 모의실험에서, 변화하는 고유치에 따른 분할 비등방성 값의 변동 추이를 알아볼 수 있었다. 그리고 확산 주축의 크기가 비등방성을 좌우하는 것이 아니라, 세 확산 주축의 조합으로 비등방성의 정도를 표현한다는 것을 확인할 수 있었다. 확산 주축 방향의 고유치들을 분리하여 영상화 함으로써, 뇌의 병변에 의한 비등방성의 변화의 원인이 확산 주축의 어떠한 변화에 의해 발생하는 것인지 확인할 수 있을 것으로 기대된다.

• 호남수학학술지
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• 제45권4호
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• pp.648-654
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• 2023

Schwarz lemma at the non-smooth boundary point for holomorphic self-map on the intersection of two balls in ℂ² is obtained. At the complex tangent point in the corner of the boundary of the domain, the tangential eigenvalue of the complex Jacobian of the holomorphic map is estimated if the map is transversal.

• 소음진동
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• 제8권3호
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• pp.408-419
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• 1998

Dynamic characteristics are investigated when a nonlinear system showing periodic and chaotic responses under harmonic excitation is exposed to random perturbation. Approach for both qulitative and quantitative analysis of the noise effect in a nonlinear system under harmonic excitation is presented. For the qualitative analysis, Lyapunov exponents are calculated and Poincar map is illustrated. For the quatitative analysis. Fokker-Planck equatin is solved numerical by means of a Path-integral solution procedure. Eigenvalue problem obtained from the numerical caculation is solved and the relation of eigenvalue, eigenvector and chaotic motion is investigated.

• 대한기계학회논문집A
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• 제32권11호
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• pp.930-936
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• 2008

This paper studies the effect of pad at initial stage and wear during braking on the dynamic contact pressure distribution. Wear is influenced by variable factor (contact pressure, sliding speed, radius, temperature) during dynamic braking and variation in contact pressure distribution. Many researchers have conducted complex eigenvalue analysis considering wear characteristic with Lim and Ashby wear map. The conventional analysis method is assumed the pad has smooth and flat surfaces. The purpose of this paper is to validate that wear rate induced by braking is considered for the precise squeal prediction. After obtaining pad wear from experiment, it is incorporated with FE model of brake system. Finally, the comparisons in fugitive nature of squeal will be carried out between the complex eigenvalue analysis and noise dynamometer experiment.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.89-90
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• 2008

This paper studies the effect of pad at initial stage and wear during braking on the dynamic contact pressure distribution. Wear is influenced by variable factor (contact pressure, sliding speed, radius, temperature) during dynamic braking and variation in contact pressure distribution. Many researchers have conducted complex eigenvalue analysis considering wear characteristic with Lim and Ashby wear map. The conventional analysis method is assumed the pad has smooth and flat surfaces. The purpose of this paper is to validate that wear rate induced by braking is considered for the precise squeal prediction. After obtaining pad wear from experiment, it is incorporated with FE model of brake system. Finally, the comparisons in fugitive nature of squeal will be carried out between the complex eigenvalue analysis and noise dynamometer experiment.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 추계학술대회 논문집
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• pp.264-270
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• 2011

The goal of this study is a stability evaluation through eigenvalue and rotor dynamics analysis of the vacuum pump. The vacuum pump used is a roots type pump, one of the dry middle vacuum pumps, is necessary at the procedure to produce semiconductor and display. The eigenvalue evaluation is solved by numerical analysis through using Modal test and 2D 3D models. Both the experiment and the analysis result are similar, the analysis result using 2D is more oculate the 3D model comparing with test result. So rotor dynamic evaluation is performed through using 2D model. Rotor dynamic evaluation used the campbell diagram and root locus map which were acquired by complex eigenvalue analysis. And we checked minimum clearance of vacuum pump composition between two rotors through unbalance response analysis. Thus, vacuum pump, the target object of this study, was evaluated to be operated stably.

• 대한전기학회논문지:시스템및제어부문D
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• 제54권6호
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• pp.417-422
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• 2005

This paper presents an EMG pattern classification method to identify motion commands for the control of the artificial arm by SOM-TVC(self organizing map - tracking Voronoi cell) based on neural network with a feature parameter. The eigenvalue is extracted as a feature parameter from the EMG signals and Voronoi cells is used to define each pattern boundary in the pattern recognition space. And a TVC algorithm is designed to track the movement of the Voronoi cell varying as the condition of additive noise. Results are presented to support the efficiency of the proposed SOM-TVC algorithm for EMG pattern recognition and compared with the conventional EDM and BPNN methods.

• Kyungpook Mathematical Journal
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• 제58권4호
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• pp.589-597
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• 2018

For $A,B{\in}M_2(\mathbb{C})$, let the Jordan product be AB + BA and G(A) the eigenvalue inclusion set, the Gershgorin set of A. Characterization is obtained for maps ${\phi}:M_2(\mathbb{C}){\rightarrow}M_2(\mathbb{C})$ satisfying $$G[{\phi}(A){\phi}(B)+{\phi}(B){\phi}(A)]=G(AB+BA)$$ for all matrices A and B. In fact, it is shown that such a map has the form ${\phi}(A)={\pm}(PD)A(PD)^{-1}$, where P is a permutation matrix and D is a unitary diagonal matrix in $M_2(\mathbb{C})$.

• Genomics & Informatics
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• 제17권4호
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• pp.39.1-39.20
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• 2019

Analyzing patterns in data points embedded in linear and non-linear feature spaces is considered as one of the common research problems among different research areas, for example: data mining, machine learning, pattern recognition, and multivariate analysis. In this paper, data points are heterogeneous sets of biosequences (composite data points). A composite data point is a set of ordinary data points (e.g., set of feature vectors). We theoretically extend the derivation of the largest generalized eigenvalue-based distance metric D_ij(γ₁) in any linear and non-linear feature spaces. We prove that D_ij(γ₁) is a metric under any linear and non-linear feature transformation function. We show the sufficiency and efficiency of using the decision rule $\bar{{\delta}}_{{\Xi}i}$(i.e., mean of D_ij(γ₁)) in classification of heterogeneous sets of biosequences compared with the decision rules min_𝚵iand median_𝚵i. We analyze the impact of linear and non-linear transformation functions on classifying/clustering collections of heterogeneous sets of biosequences. The impact of the length of a sequence in a heterogeneous sequence-set generated by simulation on the classification and clustering results in linear and non-linear feature spaces is empirically shown in this paper. We propose a new concept: the limiting dispersion map of the existing clusters in heterogeneous sets of biosequences embedded in linear and nonlinear feature spaces, which is based on the limiting distribution of nucleotide compositions estimated from real data sets. Finally, the empirical conclusions and the scientific evidences are deduced from the experiments to support the theoretical side stated in this paper.

• Communications for Statistical Applications and Methods
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• 제28권5호
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• pp.477-491
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• 2021

The Markov modulated Brownian motion is a substantial generalization of the classical Brownian Motion. On the other hand, the Markovian arrival process (MAP) is a point process whose family is dense for any stochastic point process and is used to approximate complex stochastic counting processes. In this paper, we consider a superposition of the Markov modulated Brownian motion (MMBM) and the Markovian arrival process of jumps which are distributed as the bilateral ph-type distribution, the class of which is also dense in the space of distribution functions defined on the whole real line. In the model, we assume that the inter-arrival times of the MAP depend on the underlying Markov process of the MMBM. One of the subjects of this paper is introducing how to obtain the first passage probabilities of the superposed process using a stochastic doubling algorithm designed for getting the minimal solution of a nonsymmetric algebraic Riccatti equation. The other is to provide eigenvalue and eigenvector results on the superposed process to make it possible to apply the GTH-like algorithm, which improves the accuracy of the doubling algorithm.