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Research Strategy with a Slightly Different Focus

Chihiro Matsui
Assistant Professor, Research and Development Initiative, Chuo University
Area of Specialization: Non-Volatile Semiconductor Memory Systems

Special feature for commemorating the 20th anniversary of establishment of Research and Development Initiative, Chuo University

This year, Research and Development Initiative, Chuo University commemorates the 20th anniversary of establishment. Since it was established in July 1999, it has been tackling problems with the actual society, for the purpose of developing a sustainable society, as a research center with the mission to achieve collaboration among industry, government, and academia and deepen exchanges for research. Over the past two decades, more than 100 research units have been organized, and many research outcomes that are influential academically and socially have been produced thanks to the efforts of a lot of participating researchers.

This special feature is focused on researchers participating in ongoing research units, and describes their research activities, to introduce some of research outcomes at Research and Development Initiative.

Research on high-speed non-volatile semiconductor memory systems

I conduct research on memory systems using high-speed non-volatile semiconductor memories. Non-volatile semiconductor memory has capability of saving data without the need to supply power. Different types of non-volatile semiconductor memory have different advantages and disadvantages. For example, NAND flash memory is widely used as the storage medium for large-capacity SSD and USB. On the other hand, magnetoresistive random-access memory (MRAM), resistive random-access memory (ReRAM), and phase-change random access memory (PRAM) are representative types of high-speed non-volatile semiconductor memory. In recent years, a large amount of research is being conducted on these high-speed non-volatile semiconductor memories for usage such as main memory, storage, and in-storage computing.

In the Data Centric Computing Unit, my research has focused on high-speed storage using high-speed non-volatile semiconductor memory. By using high-speed non-volatile semiconductor memory as the storage medium, we expect increases in speed and power of about 10 times compared to using only NAND flash memory. On the other hand, the speed of reading/writing and the available memory capacity differ depending on the types of non-volatile semiconductor memory. Therefore, I am devising a storage system which can manage various types of non-volatile semiconductor memory depending on the storage usage. Furthermore, since the workload differs depending on the storage usage, I conducted researches on what types of non-volatile semiconductor memory is required for each workload. I also published a research work on a system for autonomously adjusting memory capacity in storage using various types of high-speed non-volatile semiconductor memory.

Co-design of memory devices, circuits, and systems

I have been conducted my research at Takeuchi Laboratory in the Department of Electrical, Electronic, and Communication Engineering, Faculty of Science and Engineering of Chuo University. Broadly speaking, Takeuchi Laboratory do research on 3 areas: memory devices, circuits, and memory systems. Because Takeuchi Laboratory conducts research on multiple fields, I consult with Professor Takeuchi, laboratory staff, and students in order to aggregate diverse knowledge and technology for new research themes. When I first joined Takeuchi Laboratory, I started by researching memory systems. After obtaining my Ph.D., I now perform research while studying memory devices and circuits. In June 2019, I presented the results of our research on storage by co-designing memory devices, circuits, and memory systems at the VLSI Symposium, which is a large international conference on semiconductors.

The research projects which I was involved in include interdisciplinary debate with researchers at other universities and corporations. In particular, Takeuchi Laboratory performs several joint research with corporations. We also receive support from staff members at the Research and Development Initiative. Our research process consists of framing problems from corporate researchers into problems which can be solved. We then propose solution and engage in demonstration using simulations or measurement. I am overjoyed that I have been able to write academic papers on these research results and give presentations at academic conference. A major benefit of working at a university is the ability to receive frank opinions from researchers at domestic and foreign universities and corporations. As a result, I am able to look beyond immediate problems, consider a vision for future society, and keep my motivation high.

Life with a slightly different focus

When reflecting back upon my life, I have always chosen a different starting point than others. For example, all of my friends entered high schools, but I chose to enroll at a technical college. This decision had a major impact on my path and way of thinking later in life. At the time that I enrolled at the technical college, I did not intend to do anything that is unusual; rather, I was simply following what I found most interesting. Afterwards, I continued to make decisions based on what I found intuitively interesting. For my research, instead of entering major fields where countless researchers are aiming high, I prefer themes which involve creating new fields. When contemplating a new research theme, I will concentrate and read a dozen academic papers on a single theme. Sometimes, when I am thinking of something completely different, I will have a flash of inspiration during which I can see the connection between different themes A and B. This makes me so excited. The way in which I conduct research has been greatly influenced by my advisor Professor Takeuchi.

I have always focused on diligently writing academic papers related to my current research. This has taken me quite far--I have had 11 papers published in academic journals and have given presentations at 30 international conferences. In particular, obtaining my Ph.D. has greatly expanded my possibilities. Every time that my name is published in an academic paper or I give a research presentation in front of numerous researchers, I feel that I am in a wonderful position which I never could have imagined just a few years ago. Moving forward, I will continue my research while imagining a lifestyle in which high-speed non-volatile semiconductor memory makes data a more intimate part of our daily lives without any special consciousness by the user, and makes it easier for us to utilize data in our lifestyle.

Chihiro Matsui
Assistant Professor, Research and Development Initiative, Chuo University
Area of Specialization: Non-Volatile Semiconductor Memory Systems
Chihiro Matsui is an assistant professor of Research and Development Initiative, Chuo University. She graduated from the Department of Electronic Engineering in Tokyo National College of Technology. She graduated from the Department of Physics in the School of Science, Ochanomizu University, and completed the Master’s degree in Material Science in the Graduate School of Humanities and Sciences, Ochanomizu University. After working at precision equipment companies, she completed the Doctoral Program in Information Security Science in the Graduate School of Science and Engineering, Chuo University in March 2018. She holds a Ph.D. in engineering. She has her current position since April 2018.