Masakazu SENGOKU　 Professor and Dr. Eng. IEEE Fellow, IEICE Fellow Department of Information Engineering Faculty of Engineering (Graduate School of Science and Technology) NIIGATA UNIVERSITY 2-8050, Ikarashi, Niigata 950-2181, Japan E-mail: sengoku@ie.niigata-u.ac.jp

Sengoku’s professional expertise encompasses applied graph theory, especially its application to circuits, signal processing and communication network systems. He proposed a method of realizing a graph from a given set of hybrid-trees, which is a nice generalization of a problem of realization of a graph from a set of tree. The concept of hybrid tree is associated with hybrid analysis of electrical circuits and also principal partition of a graph. The concept is useful for the analysis and synthesis for active circuits. He broke a new field of location theory at flow networks and proposed some new algorithms to solve the location problems. He also developed a dynamic channel assignment technology in a cellular mobile communication system using graph theoretical algorithm, which realizes great improvement on the channel utilization, and signal processing technology for radar remote sensing.

2 Research Fields and Areas of Interest

• Graph Theoretical Research on Electrical Network
• Hybrid Trees and Their Some Properties
• Maximal Circuit-free and Cutset-free Subgraphs and Hybrid Trees
• Realization of a Set of Hybrid Trees
• Hybrid Tree Graphs
• An Operator in Signal Flow Graphs and Its Applications
• Location Theory on Networks
• Theories of Functions Expressing the Mediality of a Point in Metric Space
• A Function Measuring the Centrality (or Mediality) of Edges in an Undirected Network with Edge-Capacity
• A Fault Diagnosis in a Nonlinear Location Network
• Location Problems on Undirected Flow Networks
• Mobile Communications
• Dynamic Channel Assignment Technology in Cellular Systems
• Rearrangement Methods of Dynamic Channel Assignment
• Graph Theoretical Considerations of Channel Offset Systems in a Cellular Mobile System
• An Approach to Dynamic Channel Assignment in a Cellular Mobile Communication System Using a Neural Network
• Signal Processing
• Signal Processing Technology for Radar Remote Sensing
• FM-CW radar design for detecting objects in snow media

3  Professional Societies

1. Fellow (IEEE), since 2001
2. Senior Member since 1994(CAS, VT), The Institute of Electrical and Electronics Engineers (IEEE), Member since 1972(CAS, VT)
3. Fellow, The Institute of Electronics, Information and Communication Engineers (IEICE)
4. Member,  the Information Processing Society of Japan
5. Member, Japan Society for Industrial and Applied Mathematics.

4   Awards

1. Best Paper Award,  IEICE(The Institute of Electronics, Information and Communication Engineers),  1998
2. Best Paper Award,  IEICE(The Institute of Electronics, Information and Communication Engineers),  1997
3. Best Paper Award,  IEICE(The Institute of Electronics, Information and Communication Engineers),  1996
4. IEEE ICNNSP Best Paper Award, 1995 (International Conference on Neural Networks and Signal Processing)
5. Best Paper Award,  IEICE(The Institute of Electronics, Information and Communication Engineers),  1992

5   Major Publications

5.1 Graph Theoretical Research on Electrical Network

• ``Hybrid Trees and Hybrid Tree Graphs,''
  IEEE Trans. Circuits and Systems, Vol. CAS-22, No. 10, pp. 786-790, 1975. 
• ``On Hybrid Tree Graphs,''
  The Journal of the Institute of Electronics and Communication Engineers, Vol.57-A, No.5, pp.353-359, 1974. 
• ``On the Realization of a Set of Hybrid Trees,''
  The Journal of the Institute of Electronics and Communication Engineers, Vol.55-A, No.2, pp.60-67, 1972 
• ``An Operator in Signal Flow Graphs and Its Applications,''
  IEEE Transactions on Circuits and Systems, Vol. 35, no. 11, pp. 1383-1392 (Nov. 1988)

5.2 Location Theory on Networks

• ``On a Generalization of a Covering Problem Called Single Cover on Undirected Flow Networks,''
  IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, Vol. E80-A, no. 3, pp. 544-550 (Mar. 1997) 
• ``Problems of Where to Locate p-Sinks in a Flow Network,''
  Transactions of IEICE A, Vol. J78-A, no. 8, pp. 938-946 (Aug. 1995) 
• ``Location Problems on Undirected Flow Networks,''
  IEICE Transactions on Communication, Electronics, Information and Systems, Vol. E73, no. 12, pp. 1989-1993 (Dec. 1990) 
• ``On a Function for the Vulnerability of a Directed Flow Network,''
  Networks, Vol. 18, pp. 73-83 (1988) 
• ``A Fault Diagnosis in a Nonlinear Location Network,''
  Journal of the Franklin Institute, Vol. 323, no. 3, pp. 395-405 (1987)

5.3 Graph/Network theory and its application to Mobile Communications

• ``Characteristics of Dynamic Channel Assignment in Cellular Systems with Reuse Partitioning,''
  IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, Vol. E79, no. 7, pp. 983-989 (July 1996) 
• ``A Flexible Channel Assignment Strategy using an Artificial Neural Network in a Cellular Mobile Communication System,''
  IEICE Transactions on Fundamentals of Electronics, Communications and Sciences, Vol. E78-A, no. 6, pp. 693-700 (June 1995) 
• ``Development in graph-and/or Network-theoretic Research of Cellular Mobile Communication Channel Assignment Problems,''
  IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, Vol. E77-A, no. 7, pp. 1117-1124 (July 1994) 
• ``Graph Theoretical Considerations of Channel Offset Systems in a Cellular Mobile System,''
  IEEE Transactions on Vehicular Technology, Vol. 40, no. 2, pp. 405-412 (May 1991) 
• ``Telephone Traffic in a Mobile Radio Communication System Using Dynamic Frequency Assignment,''
  IEEE Trans. Vehicular Technology. Vol.VT-29, No.2, pp. 270-278, 1980 
• ``A Dynamic Frequency Assignment Algorithm in Mobile Radio Communication Systems,''
  the Trans. of IECE. (IECE: Institute of Electronics and Communication Engineers), Vol. E 61, No. 7, pp. 527-533, 1978.
• ``Neural Networks for Cellular Mobile Communication Systems,''
  Proceedings of  1995  IEEE International Conference on Neural Networks and  Signal Processing (ICNNSP'95), Vol. 1, pp. 345?348, 1995-12

5.4 Others: Signal Processing Technology for Radar Remote Sensing etc.

• ``Using a van-mounted FM-CW radar to detect corner-reflector road-boundary markers,''
  IEEE Trans. Instrument Measurement, Vol.45, no.4, pp.793-799, Aug. 1996 
• ``Two-dimensional and full polarimetric imaging by a synthetic aperture FM-CW radar,''
  IEEE Trans. Geoscience Remote Sensing, Vol.33, no.2, pp.421-427, Mar. 1995 
• ``Detection of objects buried in sandy ground by a synthetic aperture FM-CW radar,''
  IEICE Trans. Communications, Vol. E76-B, no.10,  pp.1297-1304, Oct. 1993 
• ``Detection of objects by synthetic aperture FM-CW radar,''
  IEICE Trans., Vol. J74-B-II, no.7, pp.413-420, July 1991 
• ``Detection of objects buried in wet snowpack by an FM-CW radar,''
• IEEE Trans. Geoscience Remote Sensing, Vol.29, no.2, pp.201-208, Mar. 1991