研究者データベース

今井 英幸(イマイ ヒデユキ)
情報科学研究院 情報理工学部門 数理科学分野
教授

基本情報

所属

  • 情報科学研究院 情報理工学部門 数理科学分野

職名

  • 教授

学位

  • 工学修士(北海道大学)
  • 博士(工学)(北海道大学)

J-Global ID

研究キーワード

  • 統計学   Statistics   

研究分野

  • 情報通信 / 統計科学

所属学協会

  • 日本行動計量学会   日本統計学会   

研究活動情報

論文

  • Mariko Tai, Mineichi Kudo, Akira Tanaka, Hideyuki Imai, Keigo Kimura
    Pattern Recognition 123 108399 - 108399 2022年03月
  • Akira TANAKA, Masanari NAKAMURA, Hideyuki IMAI
    IEICE Transactions on Information and Systems E105.D 1 116 - 122 2022年01月01日
  • Unhawa Ninrutsirikun, Hideyuki Imai, Bunthit Watanapa, Chonlameth Arpnikanondt
    Wireless Personal Communications 115 4 2897 - 2916 2020年12月 [査読有り]
  • Akira Tanaka, Hideyuki Imai
    ICASSP 2020 - 2020 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP) 2020年05月 [査読有り][通常論文]
  • Hideyuki IMAI
    IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences E103.A 2 580 - 581 2020年02月01日 [査読有り]
  • A Fast Cross-Validation Algorithm for Kernel Ridge Regression by Eigenvalue Decomposition
    田中 章, 今井 英幸
    IEICE Transactions on Electronics, Communications and Computer Sciences E102-A 9 1317 - 1320 2019年09月 [査読有り][通常論文]
  • Hiroaki OKABE, Chikara SHIMIZU, Maiko YAMAMOTO, Rei KIKUCHI, Akiko MINAMI, Yi-Fan CHEN, Hideyuki IMAI, Masahiro MIZUTA, Zhen CHEN, Hitoshi CHIBA, Shu-Ping HUI
    Analytical Sciences 34 9 1043 - 1047 2018年09月10日 [招待有り]
  • Jana Backhus, Ichigaku Takigawa, Hideyuki Imai, Mineichi Kudo, Masanori Sugimoto
    IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES E100A 3 865 - 876 2017年03月 [査読有り][通常論文]
     
    In this paper, we introduce a self-constructive Normalized Gaussian Network (NGnet) for online learning tasks. In online tasks, data samples are received sequentially, and domain knowledge is often limited. Then, we need to employ learning methods to the NGnet that possess robust performance and dynamically select an accurate model size. We revise a previously proposed localized forgetting approach for the NGnet and adapt some unit manipulation mechanisms to it for dynamic model selection. The mechanisms are improved for more robustness in negative interference prone environments, and a new merge manipulation is considered to deal with model redundancies. The effectiveness of the proposed method is compared with the previous localized forgetting approach and an established learning method for the NGnet. Several experiments are conducted for a function approximation and chaotic time series forecasting task. The proposed approach possesses robust and favorable performance in different learning situations over all testbeds.
  • TANAKA Akira, IMAI Hideyuki
    IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences 100 3 877 - 887 電子情報通信学会(The Institute of Electronics, Information and Communication Engineers / IEICE) 2017年 
    The solution of the standard 2-norm-based multiple kernel regression problem and the theoretical limit of the considered model space are discussed in this paper. We prove that 1) The solution of the 2-norm-based multiple kernel regressor constructed by a given training data set does not generally attain the theoretical limit of the considered model space in terms of the generalization errors, even if the training data set is noise-free, 2) The solution of the 2-norm-based multiple kernel regressor is identical to the solution of the single kernel regressor under a noise free setting, in which the adopted single kernel is the sum of the same kernels used in the multiple kernel regressor; and it is also true for a noisy setting with the 2-norm-based regularizer. The first result motivates us to develop a novel framework for the multiple kernel regression problems which yields a better solution close to the theoretical limit, and the second result implies that it is enough to use the single kernel regressors with the sum of given multiple kernels instead of the multiple kernel regressors as long as the 2-norm based criterion is used.
  • Hideaki Konno, Mineichi Kudo, Hideyuki Imai, Masanori Sugimoto
    Speech Commun. 83 10 - 20 2016年
  • Sadamori Koujaku, Ichigaku Takigawa, Mineichi Kudo, Hideyuki Imai
    SOCIAL NETWORKS 44 143 - 152 2016年01月 [査読有り][通常論文]
     
    Discovery of cohesive subgraphs is an important issue in social network analysis. As representative cohesive subgraphs, pseudo cliques have been developed by relaxing the perfection of cliques. By enumerating pseudo clique subgraphs, we can find some structures of interest such as a star-like structure. However, a little more complicated structures such as a core/periphery structure is still hard to be found by them. Therefore, we propose a novel pseudo clique called p-dense core and show the connection with the other pseudo cliques. Moreover, we show that a set of p-dense core subgraphs gives an optimal solution in a graph partitioning problem. Several experiments on real-life networks demonstrated the effectiveness for cohesive subgraph discovery. (C) 2015 Elsevier B.V. All rights reserved.
  • Jana Backhus, Ichigaku Takigawa, Hideyuki Imai, Mineichi Kudo, Masanori Sugimoto
    NEURAL INFORMATION PROCESSING, ICONIP 2016, PT IV 9950 538 - 546 2016年 [査読有り][通常論文]
     
    In this paper, we propose a weight-time-dependent (WTD) update approach for an online EM algorithm applied to the Normalized Gaussian network (NGnet). WTD aims to improve a recently proposed weight-dependent (WD) update approach by Celaya and Agostini. First, we discuss the derivation of WD from an older time-dependent (TD) update approach. Then, we consider additional aspects to improve WD, and by including them we derive the new WTD approach from TD. The difference between WD and WTD is discussed, and some experiments are conducted to demonstrate the effectiveness of the proposed approach. WTD succeeds in improving the learning performance for a function approximation task with balanced and dynamic data distributions.
  • Jana Backhus, Ichigaku Takigawa, Hideyuki Imai, Mineichi Kudo, Masanori Sugimoto
    ARTIFICIAL NEURAL NETWORKS AND MACHINE LEARNING - ICANN 2016, PT I 9886 444 - 452 2016年 [査読有り][通常論文]
     
    In this paper, a Normalized Gaussian Network (NGnet) is introduced for online sequential learning that uses unit manipulation mechanisms to build the network model self-constructively. Several unit manipulation mechanisms have been proposed for online learning of an NGnet. However, unit redundancy still exists in the network model. We propose a merge mechanism for such redundant units, and change its overlap calculation in order to improve the identification accuracy of redundant units. The effectiveness of the proposed approach is demonstrated in a function approximation task with balanced and imbalanced data distributions. It succeeded in reducing the model complexity around 11% on average while keeping or even improving learning performance.
  • 田中 章, 竹林裕史, 瀧川一学, 今井英幸, 工藤峰一
    IEICE Transactions on Fundamentals of Electronics, Communications and Computer Science E98-A 11 2315 - 2423 2015年11月 [査読有り][通常論文]
  • Sadamori Koujaku, Mineichi Kudo, Ichigaku Takigawa, Hideyuki Imai
    Proceedings of the 24th International Conference on World Wide Web Companion, WWW 2015, Florence, Italy, May 18-22, 2015 - Companion Volume 793 - 798 ACM 2015年 [査読有り][通常論文]
  • マルチカーネル回帰とアンサンブルカーネル回帰の汎化誤差解析
    田中 章, 瀧川 一学, 今井 英幸, 工藤 峰一
    第29回信号処理シンポジウム講演論文集 120 - 123 2014年11月 [査読無し][通常論文]
  • 田中 章, 瀧川 一学, 今井 英幸, 工藤 峰一
    Proceedings of the 6th Asian Conference on Machine Learning (ACML2014) 2014年11月 [査読有り][通常論文]
  • 斜射影を用いたMUSIC法によるDOA推定
    田中 章, 今井 英幸
    日本音響学会2014年春季研究発表会講演論文集 CD-ROM:3-2-1  2014年03月 [査読無し][通常論文]
  • Akira Tanaka, Hideyuki Imai
    IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES E97A 1 322 - 330 2014年01月 [査読有り][通常論文]
     
    In signal restoration problems, we expect to improve the restoration performance with a priori information about unknown target signals. In this paper, the parametric Wiener filter with linear constraints for unknown target signals is discussed. Since the parametric Wiener filter is usually defined as the minimizer of the criterion not for the unknown target signal but for the,filter, it is difficult to impose constraints for the unknown target signal in the criterion. To overcome this difficulty, we introduce a criterion for the parametric Wiener filter defined for the unknown target signal whose minimizer is equivalent to the solution obtained by the original formulation. On the basis of the newly obtained criterion, we derive a closed-form solution for the parametric Wiener filter with linear constraints.
  • Akira Tanaka, Hideyuki Imai
    2014 IEEE WORKSHOP ON STATISTICAL SIGNAL PROCESSING (SSP) 300 - 303 2014年 [査読有り][通常論文]
     
    In the MUSIC-based direction of arrival (DOA) estimation technique, the orthogonal projection of a steering vector onto the socalled noise subspace plays a crucial role. The noise subspace is defined as the orthogonal complement of the signal subspace spanned by the unknown true steering vectors of target signals, which implies that the correlation structure of noise does not contribute to the DOA estimation performance after the signal subspace is specified. In this paper, we introduce a novel noise subspace, called the proper noise subspace, which is a complementary subspace of the signal subspace and reflects the correlation structure of the noise; and construct a novel MUSIC-based DOA estimation algorithm based on the oblique projector onto the proper noise subspace along the signal subspace.
  • Akira Tanaka, Ichigaku Takigawa, Hideyuki Imai, Mineichi Kudo
    STRUCTURAL, SYNTACTIC, AND STATISTICAL PATTERN RECOGNITION 8621 273 - 281 2014年 [査読有り][通常論文]
     
    Kernel-based learning is widely known as a powerful tool for various fields of information science such as pattern recognition and regression estimation. For the last few decades, a combination of different learning machines so-called ensemble learning, which includes learning with multiple kernels, have attracted much attention in this field. Although its efficacy was revealed numerically in many works, its theoretical grounds are not investigated sufficiently. In this paper, we discuss regression problems with a class of kernels and show that the generalization error by an ensemble kernel regressor with the class of kernels is smaller than the averaged generalization error by kernel regressors with each kernel in the class.
  • "A Sufficient Condition For Reproducing Kernel Hilbert Spaces Being Separable
    田中 章, 今井 英幸, 工藤 峰一
    第28回信号処理シンポジウム講演論文集 350 - 354 2013年11月 [査読無し][通常論文]
  • A Novel Criterion for Quality Improvement of JPEG Images Based on Image Database and Re-application of JPEG
    Katsuya Kohno, Akira Tanaka, Hideyuki Imai
    Proceedings of APSIPA Annual Summit & Conference 2012 ID:112  2012年12月 [査読有り][通常論文]
  • A. Tanaka, I. Takigawa, H. Imai, M. Kudo
    Lecture Notes in Computer Science, Structural, Syntactical and Statistical Pattern Recognition (LNCS 7626) 7626 345 - 353 2012年11月 [査読有り][通常論文]
     
    Learning based on kernel machines is widely known as a powerful tool for various fields of information science such as pattern recognition and regression estimation. An appropriate model selection is required in order to obtain desirable learning results. In our previous work, we discussed a class of kernels forming a nested class of reproducing kernel Hilbert spaces with an invariant metric and proved that the kernel corresponding to the smallest reproducing kernel Hilbert space, including an unknown true function, gives the best model. In this paper, we relax the invariant metric condition and show that a similar result is obtained when a subspace with an invariant metric exists.
  • A. Tanaka, H. Imai, K. Takamiya
    Proceedings of 2012 IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP2012) 2001 - 2004 2012年03月 [査読有り][通常論文]
  • Akira Tanaka, Hideyuki Imai, Mineichi Kudo, Masaaki Miyakoshi
    2011 IEEE INTERNATIONAL CONFERENCE ON ACOUSTICS, SPEECH, AND SIGNAL PROCESSING 2072 - 2075 2011年 [査読有り][通常論文]
     
    One of central topics of kernel machines in the field of machine learning is a model selection, especially a selection of a kernel or its parameters. In our previous work, we discussed a class of kernels forming a class of nested reproducing kernel Hilbert spaces with an invariant metric; and proved that the kernel corresponding to the smallest reproducing kernel Hilbert space, including an unknown true function, gives the optimal model. In this paper, we consider a class of kernels forming a class of nested reproducing kernel Hilbert spaces whose metrics are not always invariant and show that a similar result to the invariant case is not obtained by providing a counter example using a class of Gaussian kernels.
  • A. Tanaka, H. Imai, M. Kudo, M. Miyakoshi
    Proceedings of the 20th International Conference on Pattern Recognition (ICPR2010) 1421 - 1424 2010年08月 [査読有り][通常論文]
  • A. Tanaka, H. Imai, M. Miyakoshi
    IEEE Transactions on Signal Processing 58 7 3569 - 3577 IEEE - Institute of Electrical and Electronics Engineers 2010年07月 [査読有り][通常論文]
     
    A perfect reconstruction of functions in a reproducing kernel Hilbert space from a given set of sampling points is discussed. A necessary and sufficient condition for the corresponding reproducing kernel and the given set of sampling points to perfectly recover the functions is obtained in this paper. The key idea of our work is adopting the reproducing kernel Hilbert space corresponding to the Gramian matrix of the kernel and the given set of sampling points as the range space of a sampling operator and considering the orthogonal projector, defined via the range space, onto the closed linear subspace spanned by the kernel functions corresponding to the given sampling points. We also give an error analysis of a reconstructed function by incomplete sampling points.
  • Jun Toyama, Mineichi Kudo, Hideyuki Imai
    PATTERN RECOGNITION 43 4 1361 - 1372 2010年04月 [査読有り][通常論文]
     
    A novel approach for k-nearest neighbor (k-NN) searching with Euclidean metric is described. It is well known that many sophisticated algorithms cannot beat the brute-force algorithm when the dimensionality is high. In this study, a probably correct approach, in which the correct set of k-nearest neighbors is obtained in high probability, is proposed for greatly reducing the searching time. We exploit the marginal distribution of the k th nearest neighbors in low dimensions, which is estimated from the stored data (an empirical percentile approach). We analyze the basic nature of the marginal distribution and show the advantage of the implemented algorithm, which is a probabilistic variant of the partial distance searching. Its query time is sublinear in data size n, that is, O(mn delta) with S=o(1) in n and delta <= 1, for any fixed dimension m. (C) 2009 Elsevier Ltd. All rights reserved.
  • カーネル法を用いた回帰分析の予測精度について
    今井英幸, 田中章, 池田盛一
    電子情報通信学会技術研究報告, パターン認識・メディア理解 109 344 61 - 64 2009年12月 [査読無し][通常論文]
  • パターン認識における都市伝説
    工藤峰一, 今井英幸, 田中章, 杉山将
    電子情報通信学会技術研究報告, パターン認識・メディア理解 109 344 29 - 34 2009年12月 [査読無し][通常論文]
  • 再生核ヒルベルト空間における標本化定理」
    田中章, 今井英幸, 宮腰政明
    第24回SIPシンポジウム講演論文集 A1-2  2009年11月 [査読無し][通常論文]
  • Kozo Yamada, Hirohito Sakurai, Hideyuki Imai, Yoshiharu Sato
    KNOWLEDGE-BASED AND INTELLIGENT INFORMATION AND ENGINEERING SYSTEMS, PT II, PROCEEDINGS 5712 340 - 347 2009年 [査読有り][通常論文]
     
    In preceding studies, error rate estimators have been compared under various conditions and in most cases the population distribution was assumed to be normal. Effects of non-normality of the population have therefore not been studied sufficiently. In this study, we focused on kurtosis measure of non-normality and examined the effects of kurtosis for error rate estimators, especially resampling-based estimators. Our simulation results in two-class discrimination using a linear discriminant function suggest that it is necessary to consider non-normality of the population in comparison of estimators.
  • Mineichi Kudo, Jun Toyama, Hideyuki Imai
    KNOWLEDGE-BASED AND INTELLIGENT INFORMATION AND ENGINEERING SYSTEMS, PT II, PROCEEDINGS 5712 333 - 339 2009年 [査読有り][通常論文]
     
    Unfortunately there is no essentially faster algorithm than the brute-force algorithm for the nearest neighbor searching ill high-dimensional space. The most promising way is to find an approximate nearest neighbor in high probability. This paper describes a, novel algorithm that is practically faster than most of previous algorithms. Indeed; it runs in a sublinear order of the data, size.
  • Noisy BSS Based on Joint Diagonalization of Differences of Correlation Matrices
    A. Tanaka, H. Imai, M. Miyakoshi
    Proceedings of the 10th IASTED International Conference Signal and Image Processing (SIP 2008) 368 - 373 2008年08月 [査読有り][通常論文]
  • Wiener Implementation of Kernel Machines
    A. Tanaka, H. Imai, J. Toyama, M. Kudo, M. Miyakoshi
    Proceedings of the Fifth IASTED International Conference on Signal Processing, Pattern Recognition, and Applications (SPPRA2008) 1 - 6 2008年02月 [査読有り][通常論文]
  • A. Tanaka, H. Imai, M. Kudo, M. Miyakoshi
    Lecture Notes in Computer Science, Structural, Syntactical and Statistical Pattern Recognition (LNCS 5342) 530 - 539 Springer 2008年 [査読有り][通常論文]
  • A. Tanaka, H. Imai, M. Miyakoshi
    Proceedings of IEEE Statistical Signal Processing Workshop 2007 (SSP2007) 109 - 113 2007年08月 [査読有り][通常論文]
  • A. Tanaka, H. Imai, M. Miyakoshi
    IEICE Transactions on Fundamentals E90-A 2 419 - 428 一般社団法人電子情報通信学会 2007年02月 [査読有り][通常論文]
     
    In D.O.A. estimation, identification of the signal and the noise subspaces plays an essential role. This identification process was traditionally achieved by the eigenvalue decomposition (EVD) of the spatial correlation matrix of observations or the generalized eigenvalue decomposition (GEVD) of the spatial correlation matrix of observations with respect to that of an observation noise. The framework based on the GEVD is not always an extension of that based on the EVD, since the GEVD is not applicable to the noise-free case which can be resolved by the framework based on the EVD. Moreover, they are not applicable to the case in which the spatial correlation matrix of the noise is singular. Recently, a quotient-singular-value-decomposition-based framework, that can be applied to problems with singular noise correlation matrices, is introduced for noise reduction. However, this framework also can not treat the noise-free case. Thus, we do not have a unified framework of the identification of these subspaces. In this paper, we show that a unified framework of the identification of these subspaces is realized by the concept of proper and improper eigenspaces of the spatial correlation matrix of the noise with respect to that of observations.
  • A. Tanaka, H. Imai, M. Miyakoshi
    Proceedings of the 6th IEEE International Symposium on Signal Processing and Information Technology(ISSPIT2006) 647 - 650 2006年08月 [査読有り][通常論文]
  • Theoretical Foundations of Second-Order-Statistics-Based Blind Source Separation for Non-Stationary Sources
    A. Tanaka, H. Imai, M. Miyakoshi
    Proceedinngs of 2006 IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP2006) 600 - 603 2006年05月 [査読有り][通常論文]
  • Model Selection Using a Class of Kernels with an Invariant Metric
    A. Tanaka, M. Sugiyama, H. Imai, M. Kudo, M. Miyakoshi
    Lecture Notes in Computer Science, Structural, Syntactical and Statistical Pattern Recognition (LNCS 4109) 862 - 870 2006年 [査読有り][通常論文]
  • アフィン制約を考慮した画像復元フィルタの構成
    田中章, 今井英幸, 宮腰政明
    第20回信号処理シンポジウム講演論文集 D7-3  2005年11月 [査読無し][通常論文]
  • Image Restoration With an Affine Constraint
    A. Tanaka, H. Imai, M. Miyakoshi
    Proceedings of the fifth IASTED International Conference on Visualization, Imaging & Image Processing (VIIP2005) 326 - 331 2005年09月 [査読有り][通常論文]
  • A. Tanaka, H. Imai, M. Kudo, M. Miyakoshi
    Proceedings of the seventh International Conference on Computing Anticipatory Systems (CASYS'05) 347 - 353 2005年08月 [査読有り][通常論文]
  • 宮内 誠一, 桜井 裕仁, 今井 英幸, 佐藤 義治
    日本計算機統計学会シンポジウム論文集 19 11 - 14 日本計算機統計学会 2005年
  • A. Tanaka, H. Imai, M. Miyakoshi
    Electronics and Communications in Japan, Part 2 88 8 54 - 65 2005年 [査読有り][通常論文]
  • Image Restoration for Observation Processes with Stochastic Variation
    A. Tanaka, H. Imai, M. Miyakoshi
    Proceedings of the 8th World Multiconference on Systemics, Cyberneticsand Informatics (SCI 2004) V 92 - 96 2004年07月 [査読有り][通常論文]
  • Waweru Mwangi, 今井 英幸, 桜井 裕仁, 佐藤 義治
    計算機統計学 16 2 167 - 167 日本計算機統計学会 2004年
  • Projection Learning Based Kernel Machine Design Using Series of Monotone IncreasingReproducing Kernel Hilbert Spaces
    A. Tanaka, I. Takigawa, H. Imai, M. Kudo, M. Miyakoshi
    Lecture Notes in Artificial Intelligence (subseries of Lecture Notes in Computer Science), Knowledge-Based Intelligent Information and Engineering Systems Part.I 1058 - 1064 2004年 [査読有り][通常論文]
  • Mineichi Kudo, Hideyuki Imai, Akira Tanaka, Tetsuya Murai
    Structural, Syntactic, and Statistical Pattern Recognition, Joint IAPR International Workshops, SSPR 2004 and SPR 2004, Lisbon, Portugal, August 18-20, 2004 Proceedings 885 - 893 Springer 2004年 [査読有り][通常論文]
  • Nobuhiro Taneichi, Yuri Sekiya, Hideyuki Imai
    Annals of the Institute of Statistical Mathematics 55 4 831 - 848 2003年12月 [査読有り][通常論文]
  • 補空間成分推定に基づく特異観測過程に対する画像復元
    田中章, 今井英幸, 宮腰政明
    電子情報通信学会論文誌D-II Vol.J86-D-II 12 1745 - 1755 2003年12月 [査読有り][通常論文]
  • RW Mwangi, H Imai, Y Sato
    IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES E86A 11 2836 - 2843 2003年11月 [査読有り][通常論文]
     
    The knowledge of a good enclosure of the range of a function over small interval regions allows us to avoid convergence of optimization algorithms to a non-global point(s). We used interval slopes f [X, x] to check for monotonicity and integrated their derivative forms g[X, x], x is an element of X by quadratic and Newton methods to obtain narrow enclosures. In order to include boundary points in the search for the optimum point(s), we expanded the initial box by a small width on each dimension. These procedures resulted in an improvement in the algorithm proposed by Hansen [4].
  • 線型画像復元問題における定式化と解に関する一考察
    田中章, 今井英幸, 宮腰政明
    第18回DSPシンポジウム講演論文集 D1-1  2003年11月 [査読無し][通常論文]
  • A. Tanaka, H. Imai, M. Miyakoshi
    Proceedings of 2003 IEEE Workshop on Statistical Signal Processing (SSP'03) 173 - 176 2003年09月 [査読有り][通常論文]
  • 吉田 清隆, 今井 英幸, 佐藤 義治
    計算機統計学 16 1 21 - 29 日本計算機統計学会 2003年 
    多変量分散分析(MANOVA)における次元に関する検定問題では,LR(Likelihood Ratio)型,LH(Lawley-Hotelling)型,BNP(Bartlett-Nanda-Pillai)型の検定方式が代表的であるが,これらの帰無分布は局外母数に依存することが知られている.Yoshida et al.(2002)は,elliptical母集団の下で,上記3タイプの帰無分布に関して上界となる,局外母数に依存しない新たな検定方式を提案し,contaminated正規母集団の下では,LR型,LH型については,帰無分布に関して上限になることを証明している.本稿では,多変量t母集団における次元検定について考察し,Yoshida et al.(2002)が提案した検定方式は,contaminated正規母集団のときと同様,LR型,LH型については,帰無分布に関して上限になることを示した.
  • A. Tanaka, H. Imai, M. Miyakoshi
    Electronics and Communications in Japan, Part 3 86 3 77 - 86 2003年 [査読有り][通常論文]
  • On Duality of Constrained Least-Squares Restoration and Parametric Wiener Restoration
    田中章, 今井英幸, 宮腰政明
    第17回DSPシンポジウム講演論文集 A2-1  2002年11月 [査読無し][通常論文]
  • On Duality of Formulations in Image Restoration Problems
    A. Tanaka, H. Imai, M. Miyakoshi
    Proceedings of the 4th IASTED International Conference Signal and Image Processing 242 - 247 2002年08月 [査読有り][通常論文]
  • Relations and Differences Between Classical and Modern Formulations in Image Restoration Problems
    A. Tanaka, H. Imai, M. Miyakoshi
    Proceedings of the 6th World Multiconference on Systemics, Cybernetics and Informatics XVI 324 - 328 2002年07月 [査読有り][通常論文]
  • 分離核作用素に対する分離核型正則化一般逆行列
    田中章, 今井英幸, 宮腰政明
    電子情報通信学会論文誌A J85-A 6 730 - 734 2002年06月 [査読有り][通常論文]
  • Choosing the Parameter of Image Restoration Filters by Modified Subspace Information Criterion
    A. Tanaka, H. Imai, M. Miyakoshi
    IEICE Transaction on Fundamentals E85-A 5 1104 - 1110 2002年05月 [査読有り][通常論文]
  • Choosing the Parameter of Regularized MP-Inverses by Modified SIC in Image Restoration Problems
    A. Tanaka, H. Imai, M. Miyakoshi
    International Journal of Computing Anticipatory Systems 12 166 - 178 2002年 [査読有り][通常論文]
  • A. Tanaka, H. Imai, M. Miyakoshi
    Electronics and Communications in Japan, Part 3 85 11 9 - 17 2002年 [査読有り][通常論文]
  • 線形最適画像復元フィルタに関する一考察
    田中章, 今井英幸, 宮腰政明
    第16回DSPシンポジウム講演論文集 53 - 58 2001年11月 [査読無し][通常論文]
  • M-N-ノルム型パラメトリック射影フィルタ族による画像復元
    田中章, 今井英幸, 宮腰政明
    電子情報通信学会論文誌A J84-A 8 1063 - 1070 2001年08月 [査読有り][通常論文]
  • A Suzukawa, H Imai, Y Sato
    ANNALS OF THE INSTITUTE OF STATISTICAL MATHEMATICS 53 2 262 - 276 2001年06月 [査読有り][通常論文]
     
    This paper is intended as an investigation of parametric estimation for the randomly right censored data. In parametric estimation, the Kullback-Leibler information is used as a measure of the divergence of a true distribution generating a data relative to a distribution in an assumed parametric model M. When the data is uncensored, maximum likelihood estimator (MLE) is a consistent estimator of minimizing the Kullback-Leibler information, even if the assumed model M does not contain the true distribution. We call this property minimum Kullback-Leibler information consistency (MKLI-consistency). However, the MLE obtained by maximizing the likelihood function based on the censored data is not MKLI-consistent. As an alternative to the MLE, Oakes (1986, Biometrics, 42, 177-182) proposed an estimator termed approximate maximum likelihood estimator (AMLE) due to its computational advantage and potential for robustness. We show MKLI-consistency and asymptotic normality of the AMLE under the misspecification of the parametric model. In a simulation study, we investigate mean square errors of these two estimators and an estimator which is obtained by treating a jackknife corrected Kaplan-Meier integral as the log-likelihood. On the basis of the simulation results and the asymptotic results, we discuss comparison among these estimators. We also derive information criteria for the MLE and the AMLE under censorship, and which call be used not only for selecting models but also for selecting estimation procedures.
  • 重み付きヒルベルト空間上でのパラメトリック射影フィルタ族の構成
    田中章, 今井英幸, 宮腰政明
    第15回DSPシンポジウム講演論文集 581 - 586 2000年11月 [査読無し][通常論文]
  • 信号適応型パラメトリック射影フィルタ族による画像復元
    田中章, 今井英幸, 宮腰政明
    電子情報通信学会論文誌A J83-A 8 1011 - 1020 2000年08月 [査読有り][通常論文]
  • ノルム拘束に基づくパラメトリック射影フィルタ族の正則化
    田中章, 今井英幸, 宮腰政明
    電子情報通信学会論文誌A J83-A 6 812 - 820 2000年06月 [査読有り][通常論文]
  • パラメトリック射影フィルタ族の正則化に関する一考察
    田中章, 今井英幸, 宮腰政明
    第14回DSPシンポジウム講演論文集 210 - 206 1999年11月 [査読無し][通常論文]
  • 2次形式不等式制約を用いた射影フィルタによる画像復元
    田中章, 今井英幸, 宮腰政明
    電子情報通信学会論文誌D-II J82-D-II 3 415 - 421 1999年03月 [査読有り][通常論文]
  • 多重解像度解析におけるスケール間関係を利用した自然画像の復元
    田中章, 今井英幸, 宮腰政明
    第13回DSPシンポジウム講演論文集 141 - 145 1998年11月 [査読無し][通常論文]
  • 多重解像度解析を用いたディジタル画像の拡大
    田中章, 今井英幸, 宮腰政明, 伊達惇
    電子情報通信学会論文誌D-II J79-D-II 5 819 - 825 1996年05月 [査読有り][通常論文]
  • 宮腰 政明, 今井 英幸, 渡辺 剛憲, 伊達 惇
    日本ファジィ学会誌 8 2 310 - 321 日本知能情報ファジィ学会 1996年 
    ファジィ理論の構造モデリングへの応用としてファジィ構造モデリングが種々考案されている。FISM/Fuzzyはそのようなモデリングの一つである。このモデリングにおける具象化過程におけるファジィ推移的結合問題を生じる。ファジィ推移的結合問題は個別的な特殊解を生成する方法が散見されるのみで、解を一般的に求める方法は知られていない。ここでは、ファジィ推移的結合問題に関する解を一般的に求める方法について問題をより一般化した一般化ファジィ推移的結合問題を論じ、巾等性や反射性の条件が解の表示や解集合の広がりにどのように関係するか、これらの条件の下で一般解の集合がどのように表示されるかを考察する。併せて、解集合の代数的構造も考察する。ここで提案する方法が特殊な場合としてファジィ推移的結合問題を含み、その意味でファジィ推移的結合問題の解の一般解を求める問題が解決していることが明らかとなる。

書籍

  • On detecting interactions in Hayashi's second method of quantification. 'jointly worked'
    Modeling Decisions for Artificial Intelligence 2004年
  • Algorthm based on alternative projections for a fuzzy measure identification problem 'jointly worked'
    Information Fusion in Data Mining, Springer 2003年
  • Algorthm based on alternative projections for a fuzzy measure identification problem 'jointly worked'
    Information Fusion in Data Mining, Springer 2003年

その他活動・業績

  • BACKHUS Jana, TAKIGAWA Ichigaku, IMAI Hideyuki, KUDO Mineichi, SUGIMOTO Masanori 人工知能学会全国大会論文集(CD-ROM) 30th (0) ROMBUNNO.3E4‐3 -3E43 2016年 [査読無し][通常論文]
  • 金光 秀雄, 今井 英幸, 宮腰 政明 電子情報通信学会技術研究報告. NLP, 非線形問題 112 (301) 55 -60 2012年11月12日 
    連続な多変数多峰目的関数をもつ連続最適化問題:「最小化:f(x)制約条件x∈S(有界閉集合)」における最適解の数理構造を示す.そのために,解の近傍や(連結)(等)レベル集合を用いた解(局小点,極小値集合,最小点)の定義を示し,各解の定義間の包含関係や平坦な領域が存在する関数の場合における解概念や解の個数の違いについて述べる.本定義は,従来の解の近傍による(狭義)極小点などの定義より簡潔な定義となる.
  • 大西真一, 齋藤達彦, 山ノ井高洋, 今井英幸 ソフトサイエンス・ワークショップ講演論文集 21st 2011年
  • 大西真一, 齋藤達彦, 今井英幸, 山ノ井高洋 ファジィシステムシンポジウム講演論文集(CD-ROM) 27th 2011年
  • 大西真一, 山ノ井高洋, 今井英幸 ファジィシステムシンポジウム講演論文集(CD-ROM) 26th 2010年
  • 大西真一, 山ノ井高洋, 今井英幸 ファジィシステムシンポジウム講演論文集(CD-ROM) 25th 2009年
  • 大西真一, 山ノ井高洋, 今井英幸 ファジィシステムシンポジウム講演論文集(CD-ROM) 24th 2008年
  • Akira Tanaka, Hideyuki Imai, Mineichi Kudo, Masaaki Miyakoshi PATTERN RECOGNITION 40 (11) 2930 -2938 2007年11月 [査読無し][通常論文]
     
    Kernel machines are widely considered to be powerful tools in various fields of information science. By using a kernel, an unknown target is represented by a function that belongs to a reproducing kernel Hilbert space (RKHS) corresponding to the kernel. The application area is widened by enlarging the RKHS such that it includes a wide class of functions. In this study, we demonstrate a method to perform this by using parameter integration of a parameterized kernel. Some numerical experiments show that the unresolved problem of finding a good parameter can be neglected. (c) 2007 Pattern Recognition Society. Published by Elsevier Ltd. All rights reserved.
  • 線形制約の一般解によるパラメトリック部分射影フィルタの解釈とアフィン制約付き復元問題への応用
    田中章, 今井英幸, 宮腰政明 電子情報通信学会論文誌 J89-A (8) 679 -681 2006年 [査読無し][通常論文]
  • 大西真一, 山ノ井高洋, 今井英幸 ファジィシステムシンポジウム講演論文集(CD-ROM) 21st 2005年
  • AHPの感度分析結果を用いた代替案ウェイトについて
    大西真一, 山ノ井高洋, 今井英幸 北海学園大学工学部研究報告 32 167 -174 2005年 [査読無し][通常論文]
  • A Tanaka, H Imai, M Miyakoshi IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES E87A (8) 2144 -2151 2004年08月 [査読無し][通常論文]
     
    In terms of the formulation of the optimality, image restoration filters can be divided into two streams. One is formulated as an optimization problem in which the fidelity of a restored image is indirectly evaluated, and the other is formulated as an optimization problem based on a direct evaluation. Originally, the formulation of the optimality and the solutions derived from the formulation are identical each other. However in many studies adopting the former stream, an arbitrary choice of a solution without a mathematical ground passes unremarked. In this paper, we discuss the relation between the formulation of the optimality and the solution derived from the formulation from a mathematical point of view, and investigate the relation between a direct style formulation and an indirect one. Through these analyses, we show that the both formulations yield the identical filter in practical situations.
  • RW Mwangi, H Imai, Y Sato IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES E87A (8) 2120 -2125 2004年08月 [査読無し][通常論文]
     
    In order to produce precise enclosures from a multidimensional interval vector, we introduce a sharp interval sub-dividing condition for optimization algorithms. By utilizing interval inclusion properties, we also enhance the sampling of an upper bound for effective use in the interval quadratic method. This has resulted in an improvement in the algorithm for the unconstrained optimization problem by Hansen in 1992.
  • A Tanaka, H Imai, M Miyakoshi IEICE Transactions on Fundamentals E87A (8) 2144 -2151 2004年08月 [査読無し][通常論文]
     
    In terms of the formulation of the optimality, image restoration filters can be divided into two streams. One is formulated as an optimization problem in which the fidelity of a restored image is indirectly evaluated, and the other is formulated as an optimization problem based on a direct evaluation. Originally, the formulation of the optimality and the solutions derived from the formulation are identical each other. However in many studies adopting the former stream, an arbitrary choice of a solution without a mathematical ground passes unremarked. In this paper, we discuss the relation between the formulation of the optimality and the solution derived from the formulation from a mathematical point of view, and investigate the relation between a direct style formulation and an indirect one. Through these analyses, we show that the both formulations yield the identical filter in practical situations.
  • H Imai, D Izawa, K Yoshida, Y Sato MODELING DECISIONS FOR ARTIFICIAL INTELLIGENCE, PROCEEDINGS 3131 205 -214 2004年 [査読無し][通常論文]
     
    The method of quantification were developed and investigated for the purpose of analyzing qualitative data. In the second method of quantification, the matter of interest is to discriminate the categories of the response variable. For that purpose, numerical scores of each categories are introduced so that the categories of the response variable can be discriminated as well as possible by those score. Since the total score is the sum of each category's score, the model is an additive model. Thus, if observations have a synergism, the method fails to grasp the structure. As a consequence, the response variable seems not to be discriminated by the method. In this paper, we propose an extension of Hayashi's second method of quantification by applying a fuzzy integral approach. To use the degree of decomposition of scores, we can include interactions between categories to the model.
  • K Yoshida, H Imai, Y Sato COMMUNICATIONS IN STATISTICS-THEORY AND METHODS 33 (11-12) 2799 -2816 2004年 [査読無し][通常論文]
     
    In this paper, tests of dimensionality in the multivariate analysis of variance model under elliptical populations are considered. We show that the upper bounds proposed by Yoshida et al. [Yoshida, K., Imai. H., Sato, Y. (2002). New criteria for tests of dimensionality under elliptical populations. J Japan Statist. Soc. 32:183-192] are upper limits for likelihood ratio (LR), Lawley-Hotelling (LH), and Bartlett-Nanda-Pillai (BNP) criteria under elliptical populations.
  • Mwangi, R. W, Imai, H, Sato. Y Journal of the Japanese Society of Computational Statistics 17 (1) 21 -31 2004年 [査読無し][通常論文]
  • Image Enlargement Based on Kernel Component Estimation (共著)
    International Journal of Computing Anticipatory Systems 15, 97-108 2004年 [査読無し][通常論文]
  • H Imai, YY Yuan, Y Sato IEICE Transactions on Fundamentals of Electronics, Communications, and Computer Sciences E85A (8) 1966 -1969 2002年08月 [査読無し][通常論文]
     
    It is widely known that the family of projection filters includes the generalized inverse filter, and that the family of parametric projection filters includes parametric generalized projection filters. However, relations between the family of parametric projection filters and constrained least squares filters are not sufficiently clarified. In this paper, we consider relations between parameter estimation and image restoration by these families. As a result, we show that the restored image by the family of parametric projection filters is a maximum penalized likelihood estimator, and that it agrees with the restored image by constrained least squares filter under some suitable conditions.
  • H Imai, YY Yuan, Y Sato IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES E85A (8) 1966 -1969 2002年08月 [査読無し][通常論文]
     
    It is widely known that the family of projection filters includes the generalized inverse filter, and that the family of parametric projection filters includes parametric generalized projection filters. However, relations between the family of parametric projection filters and constrained least squares filters are not sufficiently clarified. In this paper, we consider relations between parameter estimation and image restoration by these families. As a result, we show that the restored image by the family of parametric projection filters is a maximum penalized likelihood estimator, and that it agrees with the restored image by constrained least squares filter under some suitable conditions.
  • Properties of the solution set of a fuzzy relation equation form the viewpoint of attainability (共著)
    Soft Computing 6(2), 87-91 2002年 [査読無し][通常論文]
  • Properties of the solution set of a fuzzy relation equation form the viewpoint of attainability (共著)
    Soft Computing 6(2), 87-91 2002年 [査読無し][通常論文]
  • 伊藤 孝幸, 今井 英幸, 宮腰 政明 電子情報通信学会論文誌. D-1, 情報・システム 1-情報処理 84 (9) 1454 -1456 2001年09月01日 
    本論文では, 斉次有限マルコフ連鎖を用いた遺伝的アルゴリズムの定式化に基づき, 遺伝的アルゴリズムの収束性において, 各遺伝的操作が果たす役割について考察する.
  • H Imai, Y Okahara, M Miyakoshi FUZZY SETS AND SYSTEMS 109 (3) 405 -408 2000年02月 [査読無し][通常論文]
     
    A fuzzy matrix plays an important role in system models based on a fuzzy relation, and the performance of such a system depends on forming powers of a fuzzy matrix. The powers of a general fuzzy matrix either converge or oscillate with a finite period. Many properties about convergence have been investigated, for example, sufficient conditions for convergence are shown. Moreover, a lot of properties about convergence of powers of a transitive fuzzy matrix have been considered. However, few investigations about the period have been made. In this paper, we consider the period of the powers of a general fuzzy matrix by a graph theoretical viewpoint, and show conditions for convergence under the max-min composition. (C) 2000 Elsevier Science B.V. All rights reserved.
  • H Imai, A Tanaka, M Miyakoshi IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES E82A (3) 527 -534 1999年03月 [査読無し][通常論文]
     
    Optimum filters for an image restoration are formed by a degradation operator, a covariance operator of original images, and one of noise. However, in a practical image restoration problem, the degradation operator and the covariance operators are estimated on the basis of empirical knowledge. Thus, it appears that they differ from the true ones. When we restore a degraded image by an optimum filter belonging to the family of Projection Filters and Parametric Projection Filters, it is shown that small deviations in the degradation operator and the covariance matrix can cause a large deviation in a restored image. In this paper, we propose new optimum filters based on the regularization method called the family of Regularized Projection Filters, and show that they are stable to deviations in operators. Moreover, some numerical examples follow to confirm that our description is valid.
  • H Imai, K Kikuchi, M Miyakoshi FUZZY SETS AND SYSTEMS 99 (2) 193 -196 1998年10月 [査読無し][通常論文]
     
    In a fuzzy relation equation, the properties of the solution set have been investigated especially when the basic spaces are all finite sets. However, when the basic spaces are infinite, a few properties are known. In this paper, we use the concepts of attainability and unattainability of a solution to clarify some properties of the solution set and show the condition for existence of a partially attainable solution and an unattainable one. (C) 1998 Elsevier Science B.V. All rights reserved.
  • H Imai, A Tanaka, M Miyakoshi IEEE TRANSACTIONS ON FUZZY SYSTEMS 6 (1) 90 -101 1998年02月 [査読無し][通常論文]
     
    In multivariate statistical methods, it is important to identify influential observations for a reasonable interpretation of the data structure, In this paper, we propose a method for identifying influential data in the fuzzy C-means (FCM) algorithm, To investigate such data, we consider a perturbation of the data points and evaluate the effect of a perturbation. As a perturbation, we consider two cases: one is the case in which the direction of a perturbation is specified and the other is the case in which the direction of a perturbation is not specified, By computing the change in the clustering result of FCM when given data points are slightly perturbed, we can look for data points that greatly affect the result, Also, we confirm an efficacy of the proposed method by numerical examples.
  • H Imai, Y Nakata, M Miyakoshi IEICE TRANSACTIONS ON INFORMATION AND SYSTEMS E80D (12) 1190 -1194 1997年12月 [査読無し][通常論文]
     
    We consider the situation that plural degraded images are obtained, When no prior knowledge about original images are known, these images are individually restored by an optimum restoration filter, for example, by Wiener Filter or by Projection Filter. If correlations between original images are obtained, same restoration filters based on Wiener Filter or Projection Filter are proposed, In this paper, we deal with the case that some pixels or some gaits of original images overlap, and propose a restoration method using a formulae for overlapping. The method is based on Partial Projection Filter. Moreover, we confirm an efficacy of the proposed method by numerical examples.
  • H Imai, M Miyakoshi, T Date FUZZY SETS AND SYSTEMS 90 (3) 335 -340 1997年09月 [査読無し][通常論文]
     
    Some properties of the solution set and minimal solutions of a fuzzy relation equation are considered. In this paper, we show the necessary and sufficient condition for existence of a minimal solution of a finite fuzzy relation equation defined on infinite index sets. (C) 1997 Elsevier Science B.V.
  • H Imai, A Tanaka, M Miyakoshi IEICE TRANSACTIONS ON INFORMATION AND SYSTEMS E80D (8) 788 -794 1997年08月 [査読無し][通常論文]
     
    A lot of optimum filters have been proposed for an image restoration problem. Parametric filter, such as Parametric Wiener Filter, Parametric Projection Filter, or Parametric Partial Projection Filter, is often used because it requires to calculate a generalized inverse of one operator. These optimum filters are formed by a degradation operator, a covariance operator of noise, and one of original images. In practice, these operators are estimated based on empirical knowledge. Unfortunately it happens that such operators differ from the true ones. In this paper, we show the unified formulae of inducing them to clarify their common properties. Moreover, we investigate their properties for perturbation of a degradation operator. a covariance operator of noise. and one of original images. Some numerical examples follow to confirm that our description is valid.
  • 中田 靖久, 今井 英幸, 宮腰 政明 電子情報通信学会総合大会講演論文集 1997 (2) 82 -82 1997年03月06日 
    観測画像から原画像を推定する方法において、ただ1枚の観測画像のみではなく、観測画像が複数枚入手できる場合がある。そのような場合には、1枚の画像の復元に多くの観測画像を有効に利用することが復元精度の向上において重要となる。本文では、共通部分を持つ複数枚の画像を、部分射影フィルタを用いて復元する手法を提案する。
  • 摂動法を用いた最適画像復元フィルタの評価(共著)
    電子情報通信学会論文誌 J80-D-II (3) 754 -761 1997年 [査読無し][通常論文]
  • 摂動に対する射影フィルタ族の性質(共著)
    電子情報通信学会論文誌 J80-D-II (5) 1128 -1135 1997年 [査読無し][通常論文]
  • IMAI H. IEICE Trans. J80-D-II (5) 1128 -1135 1997年 [査読無し][通常論文]
  • Evaluation of Optimum Image Restoration Filters by Perturbation of a Degradation Operator
    The Transactions of the Institute of Electronics, Information and Communication Engineers J80-D-II (3) 754 -761 1997年 [査読無し][通常論文]
  • Hideyuki Imai, Akira Tanaka, Masaaki Miyakoshi Systems and Computers in Japan 28 (8) 25 -32 1997年 [査読無し][通常論文]
     
    The image restoration problem may be considered in the framework of Hilbert space. In such a framework, the optimal restoration filter is made of a degradation operator and a covariance operator of noise. In practice, the degradation operator is determined by experimental knowledge. Unfortunately, it happens that such a degradation operator differs from the true one. Thus, the discrepancy between these operators has essential effects on the restored image. In this paper, confining ourselves to a real-valued finite-dimensional space, we present a method of evaluating how the optimal restoration filter is affected by perturbation of a degradation operator. Some numerical examples follow to confirm that our description is valid. © 1997 Scripta Technica, Inc.
  • 宮腰 政明, 今井 英幸 日本ファジィ学会誌 8 (4) 629 -638 1996年08月15日 
    ファジィ理論の構造モデリングへの応用としてファジィ構造モデリングが種々考案されている。FISM/Fuzzyはそのようなモデリングの一つである。このモデリングにおける具象化過程における若林・大内によって定式化されたファジィ推移的結合問題を生じる。筆者らは一般化ファジィ推移的結合問題を論じ、巾等性や反射性の条件が解の表示や解集合の大局的構造にどのように関係するか及び解集合の代数的構造を明らかにした。本論文では、これらの結果を踏まえて、ファジィ推移的結合問題の解集合の代数的構造を論じ、解集合が●スカラー積に関し閉じている、●∧-、∨-演算に関し閉じている(∨-, ∧-演算に関しては必ずしも閉じていない)●自明でない解をもつならば、解集合は連続体の濃度をもつ ことなどを明かにした。また、従来知られていない特殊解と解集合の関係についても●min解はファジィ推移的結合問題の第三式が制約として作用するか否かを決定する解集合上の値である●min解は解集合の極大解のx, y座標成分と一致することを明かにする。
  • 田中 章, 今井 英幸, 宮腰 政明, 伊達 惇 電子情報通信学会総合大会講演論文集 1995 (2) 57 -57 1995年03月27日 
    Mallatにより提案された多重解像度解析は,2乗可積分関数空間を解像度の異なる部分空間列により表現する.各部分空間は一つ解像度の低い部分空間と,その直交補空間の直和として表現され,Mallatはこれを直交ウェーブレットとスケール関数を用いて記述した.本研究は,この多重解像度解析により得られた各系列の相関に着目し,画像の拡大に応用する試みである.
  • ファジィデータに対する射影追跡の適用(共著)
    日本ファジィ学会誌 7 (6) 1239 -1246 1995年 [査読無し][通常論文]
  • 今井 英幸, 佐藤 義治 日本ファジィ学会誌 7 (6) 1239 -1246 1995年 [査読無し][通常論文]
     
    射影追跡はコンピュータの計算能力とグラフィック機能を利用した探索的データ解析の一手法であり, 近年のコンピュータの能力の向上に伴って注目されるようになった.射影追跡ではコンピュータによってデータの構造の特徴が最もよく現れる低次元空間(通常は一次元, あるいは二次元)を探索して射影し, グラフィック機能を用いて表示することによって, データのおおまかな潜在構造を人間のパターン認識能力を活用して調べる.このような低次元空間を自動的に探し出すために, 射影指標と呼ばれるデータ構造の興味深さを測る関数を用い, それを最大にする射影を決定する.射影追跡ではデータ構造の興味深さを非正規性として捉える.正規分布から離れるほど興味深い構造と考えるのである.したがって, 射影指標は非正規性の尺度である.ファジィデータに射影追跡法を適用するために, 射影指標として曖昧さの尺度(measures of fuzziness)を用いる方法が提案されている.射影されたデータの曖昧さが少ないほど興味深い構造と考え, 曖昧さが最も少なくなるような低次元空間にデータを射影し表示する.しかし, この方法は曖昧さだけに着目しているため, データの重要な構造であるクラスターや関数関係を見逃す可能性がある.本論文では, データの構造の興味深さと曖昧さの両方を考慮した射影追跡法を提案し, その有効性を数値実験により確かめた.
  • 吉川 毅, 今井 英幸, 宮腰 政明, 伊達 惇 全国大会講演論文集 49 113 -114 1994年09月20日 
    2次元同次二次変換はT.Date and M.Iriにより、不変式系の立場から10個の型に分類がなされている。本論文では良く知られるジュリア集合のうち、変換の反復により漸近的に原点に収束するような点の初期値の集合を収束領域、その上限を発散収束境界と呼び、その発散収束境界の形状について考察する。これは変換式によって多様な形状を示す場合があるが、同じ分類の型の中で複雑な形状が出現するパラメータと出現しないパラメータがある。今回は、そのような変換の例として方向に関する変換がロジスティック写像となるものを取り上げで考察した。
  • 宮達 安夫, 今井 英幸, 宮腰 政明, 伊達 惇 全国大会講演論文集 49 321 -322 1994年09月20日 
    画像情報を構造的に理解する上で、画像の領域分割は必要不可欠な手段であり、その手法は原画像の存在する原画像空間、あるいはその特徴量により作られる特徴空間を用いる場合の二つに分類される。本研究では特徴空間である色空間の上でクラスタリングをすることにより、画像の領域分割を行なう。従来の研究ではクラスタリング手法として主にkmeans法を用いているが、本研究ではより柔軟な分割が可能なファジィクラスタリング手法であるfuzzy cmeans(FCM)法を用いる。この手法の問題点としては初期分割の与え方により分割結果が相異なる場合があること、および他の領域に比べて小さな領域が存在するとき、この小領域をうまく分割できないことなどが可能であるファジィクラスタリングも考えられている。しかし、その手法も各クラスターの体積に制約を課す必要があり小さな領域は分割できない。そこでこの点を改善するために、重み乗数の性質を利用したファジィクラスタリングを用いることを提案する。この手法を用いると直前のステップで得られた情報を利用することができ、小さな領域に関しても分割が可能となる。
  • 宮腰 政明, 今井 英幸, 伊達 惇 北海道大學工學部研究報告 167 1 -10 1994年01月
  • 今井 英幸, 宮澤 安夫, 宮腰 政明 北海道大學工學部研究報告 167 11 -18 1994年01月
  • 対応分析における布置図の信頼性の視覚的表示法(共著)
    計算機統計学 7 (2) 17 -23 1994年 [査読無し][通常論文]
  • Graphical Representation of Reliability for Configuration of Correspondence Analysis
    Bulletin of The Conputational Statistics of Japan 7 (2) 17 -23 1994年 [査読無し][通常論文]
  • 今井 英幸, 佐藤 順一, 伊達 惇 北海道大学工学部研究報告 (165) p53 -59 1993年07月
  • 藤井 一郎, 今井 英幸, 佐藤 義治 計算機統計学 5 (2) 181 -182 1992年12月18日
  • 今井 英幸, 伊達 惇 北海道大学工学部研究報告 (161) p23 -27 1992年10月
  • 計算機統計学 5 (2) 101 -106 1992年 [査読無し][通常論文]
  • 今井 英幸, 佐藤 義治 計算機統計学 5 (2) 101 -106 1992年 [査読無し][通常論文]
     
    射影追跡法は,多次元データを直線や平面などの低次元空間に射影することによって,その構造の特徴を探索するデータ解析の手法である.射影追跡法では「射影指標」と呼ばれる射影されたデータの興味深さを表す指標を最大にする空間を探しだし,それを計算機の端末画面などに表示することによりデータのもつ構造を探索することから,計算機の計算能力やグラフィック機能を活用する手法であるといえる. 本論文ではデータが微小に変化することによって射影追跡で探しだされる射影方向がどのように影響を受けるかを感度分析的手法によって評価することを試みる.

共同研究・競争的資金等の研究課題

  • 非線形回帰分析
  • Nonlinear Regression Analysis

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