oka-pro-280Place of birth:

Kumamoto Prefecture, Japan
Date of birth:

Oct. 1945

Academic Career:
B.S. in Eng.,
Nagoya Institute of Engineering, Japan, ’68
M.S. in Mathematical Eng.,
University of Tokyo, Japan, ’70
Dr. Degree of Engineering,
University of Tokyo, Japan, ’84 Title of thesis: Study of Handwritten Chinese Character by Using Cellular Feature.
Degree:
Dr. of Engineering (Univ. of Tokyo, No.6844))
Occupational Career:
1970.4
Electrotechnical Laboratory, Researcher
1979.1 – 2002.4
Electrotechnical Laboratory, Senior reseracher
1984.7 – 1985.6
National Research Council of Canada, Visiting scientist
1988.4 – 1989.3
Part-time lecturer at Chiba University
1993.3 – 2002.3
Real World Computing Partnership, Tsukuba Research Center, chief of Information Bases Laboratory and Multi-modal Function Lablratory
1999.4 – present
Japan Advanced Institute of Science and Technology, Guest Professor
1999.4 – 2000.3
Part-time lecturer at Toyohashi University of Technology
Research Areas:

Image Processing
Pattern Recognition
Computer Vision
Artificial Intelligence
Image Retrieval
Learning and Self-organizing
Motion video understanding
Writer Identification
Song understanding
Music retrieval
Computer-Human Interface

Activities and contributions to academic societies:
1995.6 – 1997.6
Board member of Japanese Society for Artificial Intelligence
1996.6
Program chair of the 9th Annual Conference of JSAI
1995.9
Artificial Intelligence Review (Editorial Board member)
1998.8
Guest chief editor of special issue of the Transaction of IEICE
1970-present
Program member or editorial member of domestic and international conferences and journals
Contributions to the industry:
(2004)
Video Library of the Upper House started the operation from January. The part of video search by keyword was realized by using CrossMediator.
(2003)
Telephone speech retrieval system was released to the market by Neix Inc.
(2003)
Package Soft called CrossMediator was released to the market by MediaDrive Inc.
(2000-2002)
A new concept of integrated multi-media retrieval software, incorporated the concept into a specific software called “CorssMediator,” and succeeded in marketing the software through a private company. The software was recommended at 2001 Mac World New York as an excellent software and also was demonstrated both in a preliminary presentation of 2001 Intel Developer Forum by a presenter of Intel Inc. and in OracleOpenWorld 2001 Keynote by Craig Barrett, President and CEO, Intel Corporation Moscone Convention Center San Francisco, Calif. December 3, 2001.
(1980-2000)
Many private companies have developed or are under the development of software based on Oka’s works to produce commercial products.
(1970-1980
A private company developed Optical Character Reader based on my method called Cellular and Feature and marketed as character recognition package software. This application program now commands a 60 percent share of the Japanese market.
Publications: Journal Papers
(2003)
Vocabulary-free Speech Retrieval Based on Phoneme Symbol Labeling of Frame Feature: Ryuichi Oka, Takuichi NISHIMURA, Jian XIN ZHANG, Masanori IHARA, Transaction of the IEICE, Vol. J86-D-II, No.6 pp..764-775 (2003).
(2002)
On Spotting Recognition of Gesture Motion from Time-varying Image: Ryuichi OKA, Takuichi Nishimura, Hiroaki Yabe, Transactions of Information Processing Society of Japan, Vol.43, No.SIG 4 (CVIM 4), pp.54-68 (2002).

(2001)
Music Signal Spotting Retrieval by a Humming Query Using Model Driven Path Continuous Dynamic Programming: Hiroki HASHIGUCHI, TAkuichiNISHIMURA, Jian Xin ZHANG, Junko TAKITA, Ryuichi OKA, Transactions of the IEICE, Vol.J84-D-II, No.12, pp.2479-2488 (2001).
(2001)
Recognition of Human Motion Behaviors Using View-Based Aspect Model Based on Motion Change: Takuichi Nishimura, Takushi SOGO, Shinobu OGI,Ryuichi OKA, Hiroshi ISHIGURO, Transactions of the IEICE, Vol.J84-D-II, No.10 ,pp.2212-2223 (2001).
(2001)
Same Interval Retrieval from Time-Sequence Data Based on Active Search – Reference Interval-free Time-Series Active Search (RIFAS) – : TakuichiNISHIMURA, Michinao MIZUNO, Shinobu OGI, Nobuhiro SEKIMOTO, Ryuichi OKA, Transactions of the IEICE, Vol.J84-D-II, No.8 ,pp.1826-1837 (2001).
(2001)
A Method of Spotting Retrieval of Similar Intervals Using Frame-Wisely Renewing Query: Nobuhiro SEKIMOTO, Takuichi NISHIMURA, Hironobu TAKAHASHI, Ryuichi OKA, Transactions of the IEICE, Vol.J84-D-II, No.5 ,pp.747-757 (2001).
(2001)
Related Words Estimation from Unlabeled Images Using Dividing and Clustering of Images with Multiple Words: Yasuhide MORI, Hironobu TAKAHASHI, Ryuichi OKA, Transactions of the IEICE, Vol.J84-D-II, No.4 ,pp.649-658 (2001).
(2000)
A Method of Model Improvement for Spotting Recognition of Gestures Using an Image Sequence: T.Nishimura, H.Yabe, R.Oka, New Generation Computing, Vol.18, No.2, pp.89-101 (2000).
(2000)
A Method for Self-Organizing a Task Model of a Computer-Human Interaction System Using Sample Word Sequences, Shigeaki SAKURAI, Toshiro MUKAI, Ryuichi OKA, Transactions of the IEICE, Vol.J83-D-II, No.2 ,pp.827-839 (2000).
(1999)
A Method for Un-supervised Learning of a Network Model from Time Sequences – Proposal of the Incremental Path Method – : Jun TOYOURA, Takashi ENDOU, Ryuichi OKA, Transactions of the IEICE, Vol.J82-D-II,No.1,pp.61-74 (1999).
(1998)
Information Integration Architecture for Agent-Based Computer Supported Cooperative Work System: S. Nagaya, Y. Itoh, T. Endo, J. Kiyama, S. Seki and R. Oka, IEICE TRANSACTIONS on Information and Systems, Vol.E81-D, No.9, pp. 976-987 (1998).
(1998)
Spotting Method for Classification of Real World Data: Ryuichi Oka, The Computer Journal, Vol.41, No.8, pp.559-565 (1998).
(1998)
Spotting-Based Global Localization by Non-monotonic Continuous DP for a Mobile Robot Using a Sequence of Images: Takuichi NISHIMURA,Shunsuke NOZAKI, Ryuichi OKA, Transactions of IEICE, Vol.J81-D-II,No.8,pp.1876-1884 (1998).
(1998)
Adaptation to Gesture Performers by an On-line Teaching System for Spotting Recognition of Gestures from a Time-Varying Image: TakuichiNISHIMURA, Toshiro MUKAI, Shunsuke NOZAKI, Ryuichi OKA, Transactions of IEICE, Vol.J81-D-II,No.8,pp.1822-1830 (1998).
(1998)
Spotting Recognition of Gestures Using Shape Features from Grey-Scale Image Sequence: Takuichi NISHIMURA, Toshiro MUKAI, Ryuichi OKA, Transactions of IEICE, Vol.J81-D-II,No.8,pp.1812-1821 (1998).
(1998)
Weight Decreasing Reference Interval-free Continuous DP for Retrieval of Time-Sequence Pattern, Takuichi NISHIMURA, Kiyoshi HURUKAWA, Toshiro MUKAI, Ryuichi OKA, Transactions of IEICE,Vol.J81-D-II,No.3,pp.472-282 (1998).
(1998)
Spotting Recognition of Hesitated Gestures from Time-varying Images by an Extended Continuous DP with Non-monotonic Character: TakuichiNISHIMURA, Shunsuke NOZAKI, Toshiro MUKAI, Ryuichi OKA, Transactions of IEICE, Vol.J81-D-II,No.1,pp.18-26 (1998).
(1997)
Spotting Recognition of Gestures Performed by People from a Single Time-Varying Image Using Low-Resolution Features: Takuichi NISHIMURA,Shunsuke NOZAKI, Toshiro MUKAI, Ryuichi OKA, Transactions of IEICE, Vol.J80-D-II, No. 6, pp. 1563-1570 (1997).
(1997)
Location Identification System of a Mobile Robot by Using Reference Interval-free Continuous Dynamic Programming Applied to Time-Varying Images: Hiroshi KOJIMA, Yoshiaki ITOH, Ryuichi OKA, Transactions of IEICE, Vol.J80-D-II, No3, pp.724-733 (1997).
(1996)
Reference Interval-free Continuous Dynamic Programming for Spotting Speech Wave by Arbitrary Parts of a Reference Sequence of Pattern: Yoshiaki ITOH, Jiro KIYAMA, Hiroshi KOJIMA, Susumu SEKI, Ryuichi OKA, Transactions of IEICE, Vol. J79-D-II, No. 9, pp. 1474-1483 (1996).
(1996)
Topic-Independent Speech Summary and Automatic Topic Boundary Detection Using Incremental Reference Interval-free Continuous Dynamic Programming: Jiro KIYAMA, Yoshiaki ITOH, Ryuichi OKA, Transactions of IEICE,Vol. J79-D-II, No. 9, pp. 1464-1473 (1996).
(1996)
A Proposal for Ladder CDP: A New Fame-Synchronous Algorithm for Connected Word Spotting: Yoshiaki ITOH, Jiro KIYAMA, Ryuichi OKA, Transactions of IEICE, D-II,Vol.J-79-D-II, No. 1, pp. 1-10 (1996).
(1994)
Methods for Partial Sentence Recognition and Unknown Words Detection by Sentence Spotting in Continuous Speech: Yoshiaki ITOH, Jiro KIYAMA,Ryuichi OKA, Transactions of IEICE, Vol.J77-D-II, No. 8, pp.1531-1542 (1994).
(1994)
Spotting Recognition of Human Gestures from Time-Varying Images: Katushiko TAKAHASHI, Susumu SEKI, Hiroshi KOJIMA, Ryuichi OKA, Transactions of IEICE,Vol.J77-D-II, No. 8, pp. 1552-1561 (1994).
(1994)
Hierarchical labeling for integrating images and words: Ryuichi Oka, Artificial Intelligence Review, Vol. 8, pp. 123-145 (1994).
(1992)
Continuous Speech Recognition by Sentence Spotting Using the Vector Continuous Dynamic Programming Applied to Output of the Partial Matching Method: Ryuichi OKA, Transactions of IEICE, J76-D-II, No. 5, pp. 921-931 (1992).
(1989)
Speaker-Independent Spoken Word Recognition by Using the Orientation Patterns Obtained from the Vector Field of Spectrum Pattern: Hiroshi MATUMURA, Ryuichi OKA, Kazuya KOGURE, Yurie KOJIMA, Transactions of IEICE, Vol.72-D-II, No.4 , pp.487-498 (1989).
(1988)
A Learning Algorithm Based on Complementary Relationship between a Distributed Symbol Model and Connection Coefficients : Ryuichi OKA, Transactions of IEICE, Vol.71-D, No.10 (1988).
(1987)
Phonemic Recognition of Each Frame by Partial Matching Method Based on Continuous Dynamic Programming: Ryuichi OKA, Transactions of IEICE, Vol.70-D, No.5, pp.917-924 (1987).
(1987)
Cellular Frame Model for Representing Knowledge and Integrating Processing of Image Understanding: Ryuichi OKA, Transactions of IEICE, Vol.70-D-II, No.7 (1987).
(1986)
Comparison Studies on the Effectiveness Between the Vector Field of Spectrum and Spectrum for Speech Recognition: Ryuichi OKA, Transactions of IEICE, Vol.69, No.11, pp.1704-1713 (1986).
(1984)
Experimental Studies on the Connected Words Recognition Using Continuous Dynamic Programming: Satoru HAYAMIZU, Ryuichi OKA, Transactions of IECE, Vol.67-D, No.6,pp.677-684 (1984).
(1983)
Recognition of Handwritten Chinese Character Using Cell Features: Ryuichi OKA, Transactions of IECE, Vol.66-D, No.1 (1983).
(1982)
Extraction of Cell Features from Images: Ryuichi OKA, Transactions of IECE, Vol.65-D, No.10, pp.1219-1226 (1982).
(1976)
A Cellular Automaton With Figure State : Ryuichi OKA, Transactions of IECE, Vol.59-D,No.8 (1976).
(1970)
A Control Problem on the Stability of Finite Fixed Time : Ryuichi OKA, Transactions of System Information Computer Engineering, Vol.6, No.5 (1970).
Refereed Papers presented at International Conferences:
(2002)
A method of writer verification without keyword registration using feature sequences extracted from on-line handwritten sentences; HiroshiKameya, Shunji Mori,, Ryuichi Oka, Proc. of MVA2002 IAPR Workshop on Machine Vision Application, pp.479-483, December (2002).

(2002)
RWC Music Database: Popular, Classical, and Jazz Music Databases; Masataka Goto, Hiroki Hashiguchi, Takuichi Nishimura, Ryuichi Oka, Proc. of 3rd Inter. Conf. on Music Information Retrieval (ISMIR 2002), pp.287-288, October (2002).
(2001)
Real time and Time-warping Retrieval of Video Image Sequence; N.Sekimoto, T.Nishimura, H.Takahashi, R.Oka,SCI 2001, Proceedings, Volume VII, pp.298-301 (2001).
(2001)
Self-organizing an Associated Keyword Space for Text Retrieval: H.Takahashi, R.Oka, SCI 2001, Proceedings, Volume VII, pp.302-307 (2001).
(2001)
Image-driven keyword selection for searching database by image: Y.Mori, H. Takahashi, R.Oka, SCI 2001, Proceedings, Volume VII, pp.285-290 (2001).
(2001)
Auditory Scene Retrieval: T.Nishimura, N.Sekimoto, R.Oka, SCI 2001, Proceedings, Volume VII, pp.291-297 (2001).
(2001)
Real time Gesture-Speech Recognition on Personal Computer System: H.Yabe, T. Nishimura, R.Oka, SCI 2001, Proceedings, Volume VII, pp.308-311 (2001).
(2001)
Music Signal Spotting Retrieval by a Humming Query: H. Hashiguchi, T. Nishimura, J. Takita, J. Xin Zhang and R. Oka, SCI 2001, Proceedings, Vol. VII, pp.280-284 (2001).
(2000)
Spotting Recognition of Gestures by Using a Sequence of Spatially Reduced Range Image: T. Nishimura, S. Nozaki, and R. Oka, ACCV2000, vol.II, pp.937-942 (2000).
(2000)
Indexing of Human motion at Meeting Room by Analyzing Time-varying Images of Omni-directional Camera: T. Nishimura, H. Yabe, and R. Oka, ACCV 200, vol.I, pp.1-4 (2000).
(2000)
Continuous Retrieval of Video Using Segmentation-free Query: N.Sekimoto, T.Nishimura, H.Takahashi, and R.Oka, Proc. of 15th Int’l Conf. on Pattern Recognition (ICPR2000), Vol.3, pp.375-378 (2000).
(2000)
Automatic word assignment to images based on image division and vector quantization: Yasuhide Mori, Hironobu Takahashi, and Ryuichi Oka, Proc.RIAO2000, Content-Based Multimedia Information Access, vol.1, pp.285-293 (2000).
(1999)
Topic Spotting and its Description of Summary from Spontaneous Speech: M. Nakazawa, J.Zhang. R. Oka, Proceedings of Eurospeech ’99, Vol.6, pp.2447-2450, Budapest. Hungary (1999).
(1999)
Methodology for Retrieving Time Sequence Pattern: Takuichi Nishimura, Nobuhiro Sekimoto, J.Xin Zhang, Masayoshi Ihara, TakashiAkasaka,Hironobu Takahashi and Ryuichi Oka, Proc. of IWHIT/SM’99, pp.1-8, (Oct. 1999).
(1999)
Image-to-word transformation based on dividing and vector quantizing images with words: Y.Mori, H.Takahashi and R.Oka, First International Workshop on Multimedia Intelligent Storage and Retrieval Management (MISRM’99), http://www.info.uqam.ca/~misrm/papers/mori.ps, December 1999.
(1999)
Automatic task modeling for realizing a multi-modal interface system: Shigeaki Sakurai, Takashi Endo, Toshiro Mukai and Ryuichi Oka, Proceedings of ACAI-99 Workshop on Machine Learning in Human Language Technology, pp.78-87 (1999).
(1999)
Network modeling of a human-computer interaction task based on a self-organization method: Shigeaki Sakurai, Toshiro Mukai, Ryuichi Oka, Networks’99, 27-30 (1999).
(1999)
Automatic model construction for a user oriented task using speech utterances: Shigeaki Sakurai, Takashi Endo, Ryuichi Oka, KES’99, 74-77 (1999).
(1999)
Automatic acquisition of a user model based on text search by speech utterances: Sakurai, Takashi Endo, Ryuichi Oka, INES’99, pp.93-98 (1999).
(1998)
Mutual Spotting Retrieval between Speech and Video Image using Self-organized Network Databases: T. Endo, J. Xin. Zhang, M. Nakazawa and R. Oka, AMCP’98 Conference Proceedings, pp. 106-121 (1998).
(1997)
A Symbol Grounding Problem of Gesture Motion Through a Self-Organizing Network of Time-Varying Motion Images: T. Mukai, T. Nishimura, T. Endo and R. Oka, IEEE World Congress on Computational Intelligence, Proceedings, pp.721-726 (1997).
(1997)
Non-monotonic Continuous Dynamic Programming for Spotting Recognition of Hesitated Gestures from Time-Varying Images: T. Nishimura, T.Mukai and R. Oka, 3rd Asian Conference on Computer Vision(ACCV’98), Vol. 2, pp. 734-741 (1997).
(1997)
A Recognition method of Multimodal expression for 3D Space manipulation: S. Nagaya, K. Furukawa and R. Oka, Proc. WIPUI’97, pp. 65-67 (1997).
(1997)
Speech Recognition Module for CSCW sing a Microphone Array: T. Endo, S. Nagaya, M. Nakazawa, K.Furukawa, R. Oka, Proc. of Eurospeech 97, pp.1527-1530 (1997).
(1997)
Realization of Speech Retrieval using RIFCDP: K. Furukawa, M. Nakazawa, T.Endo, R.Oka, Proc. of Eurospeech 97 pp.1071-1074 (1997).
(1997)
Spotting recognition of gestures performed by people from a single time-varying image: T. Nishimura, T. Mukai and R. Oka Proc. IROS’97 Vol. 2, pp. 967-972 (1997).
(1997)
Spotting Recognition of Gestures Performed by People from a Single Time-varying Image: T. Nishimura, T. Mukai and R. Oka HCI International ’97, p. 33 (1997).
(1996)
Interaction Control Of the CSCW System using Posture Recognition: S. Nagaya, S. Seki, Y. Itoh, J. Kiyama, T, Endo and R. Oka, First International Conference on Multimodal Interface (1996).
(1996)
A Proposal of Novel Information Integration Architecture – Open Cooperative Work Space-: S.Nagaya, T. Enndo, Y. Itoh, J. Kiyama, and R. Oka, Proc. of the 1996 IEEE/SICE/RSJ International Conference on Multi sensor Fusion and Integration for Intelligent Systems, pp. 425-432 (1996).
(1996)
A Theoretical Consideration of Pattern Space Trajectory for Gesture Spotting Recognition: S. Nagaya, S. Seki, and R. Oka Proc. of the Second International Conference on Automatic Face and Gesture Recognition, pp. 72-77 (1996).
(1996)
Pattern space trajectory for Gesture spotting recognition: S. Nagaya, S. Seki* and R. Oka, 3rd France-Japan / 1st Europe-Asia Congress onMechatronics (1996).
(1996)
A Proposal of Pattern Space Trajectory for Gesture Spotting Recognition: S. Nagaya, S. Seki and R. Oka Proceedings of the 7th British Machine Vision Conference ’96, Vol. 2, pp. 625-633 (1996).
(1996)
Spotting Recognition of Human Gestures from Time-Varying Images: T. Nishimura and R. Oka, Proc. of the Second International Conference on Automatic Face and Gesture Recognition, pp. 318-322 (1996).
(1996)
Towards the Integration of Spontaneous Speech and Gesture based on Spotting Method: T. Nishimura and R. Oka, Proc. of the 1996 IEEE/SICE/RSJ International Conference on Multi sensor Fusion and Integration for Intelligent Systems, pp. 433-437 (1996).
(1996)
An Active Microphone Method for Speech Recognition Systems: T. Endo, S. Nagaya, M. Nakazawa, and R. Oka, Proc. of the 1996 IEEE/SICE/RSSJ International Conference on Multi sensor Fusion and Integration for Intelligent Systems, pp. 446-453 (1996).
(1996)
An Active Microphone Method for CSCW Systems – Toward Open co-operative Work Space – : Takashi Endo, Masayuki Nakazawa, Toshiro Mukai, Shigeki Nagaya, and Ryuichi Oka Proc. of the 1st Asia Pacific Conference on Human Computer Interaction (1996).
(1996)
The Open Cooperative Work Space: Takashi Endo, Shigeki Nagaya, Ryuichi Oka, CSCW’96, Video, Demonstration and Short paper, pp.31-32 (1996).
(1996)
Interaction control In the CSCW system using Posture Recognition: Shigeki Nagaya, Susumu Seki, Toshiro Mukai, Yoshiaki Itoh, Jiroh Kiyama, andRyuichi Oka Proc. of the 1st International Conference on Multimodal Interface, pp. 299-304 (1996).
(1996)
Multi-user Interaction Control by Gesture Recognition – Toward Open Cooperative Work Space -: S. Nagaya, T. Mukai, T. Endo, M. Nakazawa, and R. Oka, Proc. First Asia Pacific Conf. Human Computer Interaction, pp. 115-120 (1996).
(1996)
Portable Open Co-Operative Work Space – INFORMATION INTEGRATED STATION – :Toshiro Mukai, Shigeki Nagaya, Takashi Endo, MasayukiNakazawa, and Ryuichi Oka, Proc. First Asia-Pacific Conf. Human Computer Interaction(Demo Session), pp. 164-168 (1996).
(1996)
A Proposal of Ladder Continuous DP for Connected Pattern Spotting Applied to Sentence Spotting: Yoshiaki Itoh, Jiro Kiyama, and Ryuichi Oka, Proc. ICMI’96 (1996).
(1996)
A Proposal for a New Algorithm of Reference Interval-free Continuous DP for Real-time Speech or Text Retrieval: Yoshiaki Itoh, Jiro Kiyama, andRyuici Oka, Proc. ICSLP’96 (1996).
(1996)
Automatic Detection of Topic Boundaries and Keywords in Arbitrary Speech Using Incremental Reference Interval-free Continuous DP: Jiro Kiyama, Yoshiaki Itoh, and Ryuichi Oka, Proc. ICSLP ’96, Vol. 3, pp.1946-1949 (1996).
(1996)
Effect of Time-spatial Size of Motion Image for Localization by using the Spotting Method: T. Nishimura, H. Kojima, Y.Ito, A. Held, S. Nozaki, S. Nagaya, and R. Oka, Proc. of 13th International Conference on Pattern Recognition, pp. 191-195 (1996).
(1995)
Gesture Recognition using Multiple-resolution Feature of Motion Images: Susumu Seki, Shigeki Nagaya, and Ryuichi Oka Proc. Second Asian Conf. on Computer Vision, pp. 9-13 (1995).
(1995)
Novel interface system by real-time integration of speech and gesture understanding by multiple users: Yoshiaki Itoh, Jiro Kiyama, Susumu Seki, and Ryuichi Oka, Proc. IWHIT’95, pp. 17-20 (1995).
(1995)
Speech understanding and speech retrieval for TV news by using connected word spotting: Yoshiaki Itoh, Jiro Kiyama, and Ryuichi Oka, Proc. EUROSPEECH ’95, Vol. 3, pp. 2141-2144 (1995).
(1995)
Sonar Based Map Acquisition and Exploration in an Unknown Office Environment: A. Held and R. Oka, Proc. International Symposium on Intelligent Robotic Systems ’95 pp. 208-217 (1995).
(1995)
Location Identification of a Mobile Robot by Applying Reference Interval-free Continuous Dynamic Programming to Time-varying Images: H. Kojima, Y. Itoh, and R. Oka, Proc. International Symposium on Intelligent Robotic Systems ’95 pp. 337-343 (1995).
(1994)
Spotting Recognition of Motion Scenes for Navigating a Mobile Robot: H. Kojima, S. Seki, K. Takahashi, R. Oka, 4th International Conference on Intelligent Autonomous Systems (1994).
(1994)
Spotting Recognition of Motion Scenes for Robot Vision: H. Kojima, S. Seki, K. Takahashi, R. Oka, Japan- Israel Workshop on Computer Vision and Visual Communication (CVVC’94) (1994).
(1994)
Recognition of Dexterous Manipulations from Time-Varying Images: K. Takahashi, S. Seki, H. Kojima, R. Oka, Proc. 1994 IEEE Workshop on Motion of Non-Rigid and Articulate Objects, pp. 23-28 (1994).
(1994)
SENTENCE SPOTTING USING CONTINUOUS STRUCTURING METHOD: J.Kiyama, Y. Itoh, and R. Oka, Proc. 1994 Int. Conf. on Spoken Language Processing, Vol. 2, pp. 807-810 (1994).
(1993)
Sentence Spotting Applied to Partial Sentences and Unknown words: Y. Itoh, J. Kiyama, R.Oka, Proc. of International Conference on Acoustics, Speech and Signal Processing, Vol. 1, pp. 369-372 (1993).
(1993)
Spotting Partial and Complete Sentences for Spontaneous Speech: Y. Itoh, J.Kojima, R. Oka, Proc. Int. Symposium on Spoken Dialogue, pp. 109-112 (1993).
(1993)
Gesture recognition from motion image by spotting algorithm: S. Seki, K. Takahashi, R. Oka, Proc. of Asian Conference on Computer Vision, pp.759-762 (1993).
(1993)
Spotting Recognition of Human Gestures from Motion Images: K. Takahashi, S. Seki, R. Oka, Proc. 4th International Workshop on Time-Varying Image Processing and Moving Object Recognition, pp. 65-72 (1993).
(1993)
Spontaneous speech recognition by sentence spotting, J. Kiyama: Y. Itoh, R. Oka, Proc. of EUROSPEECH ’93, pp. 1053-1056 (1993).
(1988)
Speaker-independent Word Speech Recognition Using the Blurred Orientation Patterns Obtained From the Vector Field of Spectrum: Ryuichi Oka, Hiroshi Matumura, Proc. 9-th International Joint Conference on Pattern Recognition (1988).
(1986)
Object detection and recognition from 3D camera images: T.Kasvand, R. Oka, Dhome, Rioux, Int. Journal Microcomputer Application (1986).
(1985)
Continuous speech recognition on the bases on Vector Field Model for segmentation and feature extraction, and Continuous Dynamic Programming for pattern matching: Ryuichi Oka, Proc. 1985 International Conference on Acoustics, Signal and Speech Processing (1985).
(1985)
Cross-Angle transform for viewer-independent recognition of 3D objects: R. Oka, T.Kasvand,  M.Rioux, IEEE Proc. On Computer Vision and Pattern Recognition (1985).
(1985)
Phonemic recognition of each frame with Vector Field feature using Continuous Dynamic Programming: Ryuichi Oka, Proc. 1986 International Conference on Acoustics, Signal and Speech Processing (1985).
(1984)
LSI oriented architecture for Cellular Feature extraction: Ryuichi Oka, Proc. 7-th International Joint Conference on Pattern Recognition (1984).
(1982)
Handwritten Chinese-Japanese characters recognition using Cellular Feature: Ryuichi Oka, Proc. 1982 International Joint Conference on of the Chinese-Language Computer Society (1982).
(1982)
Handwritten Chinese characters recognition by using Cellular Feature: Ryuichi Oka, Proc. 6-th International Joint Conference on Pattern Recognition (1982).
(1979)
An infinite-connected words recognition system for male speakers using time-space dynamic programming: Ryuichi Oka, Proc. The 6-th International Joint Conference on Artificial Intelligence (1979).
(1978)
A new cellular automaton structure for macroscopic linear-curved features extraction: Ryuichi Oka, Proc. 4-th International Joint Conference on Pattern Recognition (1978).
Others:
(2003)
Image and integration of multi-media information (Invited lecture): Ryuichi Oka, Symposium on Intelligent Integration of Audio-Visual Information for Social Information Infrastructure, at Nagoya University, 28-th March 2003.

(2003)
How to access media data among different kinds of media information (Invited lecture) : Ryuichi Oka, Workshop on Language Processing for Integrating Modality of Media, Society of Natural Language Processing, 21-st March 2003.

(2003)
A personal view of the difficulty for solving problems in the field of artificial intelligence (Invited paper): Ryuichi Oka, Vol.18, No.1, pp. 66-72, Journal of Japanese Society for Artificial Intelligence, January 2003.

(2002)
A Brief Summary of Real World Computing Project (Invited paper) : Ryuichi Oka, The Journal of the Institute of Electronics, Information and Communication Engineers, Vol.85, No.12, pp.900-909, December 2002.

(2002)
A personal view of the difficulty for solving problems in the field of artificial intelligence (Invited lecture) : Ryuichi Oka, AI lecture, at the 16-th Annual Conference of Japanese Society for Artificial Intelligence, 2A4-01, 30-th May 2002.

(2002)
Research and Development of Information Bases Function ( Invited paper ) : Ryuichi Oka, Koichi Hashida, Journal of Japanese Society for Artificial Intelligence, Vol..17, No.2, pp. 153-162, March, 2002.
(1970 – 2001) Materials presented during 1970 – 2001but not listed here are counted up about 315 articles including invited papers, papers for invited lecture, perspective review papers, non-refereed papers etc.
Japanese Patent: total number of them is 33.
US/EP Patent: total number of them is 6