Home page of Hideo Ohashi

Hideo Ohashi, Prof. Emeritus

University of Tokyo & Kogakuin University
The Window to Society after Retirement from Engineering Education

　This top page is to transmit the proof that I am still alive and enjoying retired life, mainly to my relatives, friends and former students. A story or an event is selected from daily life and my thoughts and experience are introduced.

From Daily Life - 92: Email - Part 2

　In Part 1, I introduced my experience from the early days of email and the result of classifying 110,000 emails I've exchanged over the past 30 years. Of those 30 years, the first 17 years were during my active career, and most of the emails were business-related. However, in the following 13 years after complete retirement, such emails drastically decreased. In Part 1, emails of two different life stages are analyzed as a group.
　I am a retired pensioner over 90 with no involvement in business. In Part 2, I classify and analyze the emails I exchanged last year (2025) to see what changes have occurred.
　The classification of emails is the same as in Part 1, divided into eight categories: University, Academic society, Government agency, Enterprise, Meeting & publication, Personal, Online information, and Overseas. Last year, I sent and received a total of 3,500 emails, averaging 9.6 emails per day. For comparison, the 110,700 emails exchanged over the past 30 years average 10.1 emails per day. The table on the left above classifies and compares these daily numbers. Note that this classification does not include emails thrown into trash box or filtered out as spam.
　Comparing the past 30 years with the most recent year, 2025, the following facts emerge:
1. 　Even after retirement and stepping away from business, the decrease in the total number of emails was minimal.
2. 　Emails related to business were halved, and those for Meeting & publication ceased entirely. These decreases were compensated for by a doubling of Online information.
3. 　All types of businesses streamlined their operations by switching from postal mail to email distribution, resulting in increased frequency due to its free and convenient nature. University announcements, academic newsletters, announcements from the national government, Tokyo Metropolitan Government, and Setagaya Ward, and notifications from banks and credit companies are the example to indicate that email distribution has become the primary means of communication for businesses.
4.　 The halving of emails for personal correspondence was surprising. This is a result of the shift of interpersonal communication to social networking services (SNS) such as LINE, Instagram, and Facebook.
5. 　Online information largely consists of communication related to online businesses. When we shop online, we receive emails for confirmation and shipping from vendors, and then for prenotice and completion from delivery companies. Once we make a purchase, we start receiving frequent promotional emails from the vendor, and these continue to increase unless we unsubscribe. Notices from public utilities such as gas, water, and electricity are now also provided online. Reservations for travel, accommodation, meals, and events have shifted from telephone to online booking. Multiple emails are exchanged for a single reservation. Online information is constantly increasing and has now become an essential part of life.
6. 　The increase in emails from overseas is due to the daily arrival of newsletters from organizations such as the American Society for Engineering Education and the National Academy of Sciences.
　The internet has become deeply integrated into our society. Even for the elderly like me, emails have become necessities to live.

　The above classification is missing the following two categories:
1. 　Trash: Login notifications, one-time password notifications related to login authentication, confirmation notifications, and other emails deemed unnecessary to save are moved to Thunderbird's (mailer) trash box and finally deleted after 50 days. Based on the record of past 50 days, the average number of emails deleted per day is estimated to be 1.6.
2. 　Spam: Suspicious emails inviting users to malicious websites, phishing emails, etc., are filtered as spam and do not appear in the received emails. In my case, 96% of spam are picked out by the filtering function of Nifty mail server and stored in its spam folder for one month before finally deleted. Spam emails that slip through the filter are caught by Thunderbird's filter in my PC and stored in the spam folder for 50 days before finally deleted. I occasionally find suspicious mails that have slipped through both filters, and throw manually away into spam folder.
　The number of spam emails fluctuates considerably depending on the time of year. During the Lunar New Year period, it usually drops to less than a third of its peak. It seems that many senders of large amounts of spam are people celebrating the Lunar New Year. The number of emails filtered by Nifty server used to be around 500 per month, but recently it has decreased to around 350. I read recently a report in newspaper that 45,000 servers used for phishing and other malicious activities have been neutralized in an international joint investigation, so these efforts may be having an effect.
　Taking such fluctuations into account, I estimated that an average of 13.1 emails are filtered by Nifty per day, and 0.5 by Thunderbird, for a total of 13.6 emails.

　The breakdown of emails in 2025, including Trash and Spam, is shown in the pie chart on the right above. The fact that only a small portion of emails are useful, with spam accounting for more than half of the total, is appalling. Email offers many conveniences to everyone for free, but at the same time, it provides criminals with easy opportunities to commit fraud. This situation is likely similar in the world of SNS. In this internet age, the wisdom to avoid being deceived is essential.
　Looking at the history of email, it initially consisted mostly of business communications between acquaintances, but now it is predominantly used for communications targeting numerous clients. While its convenience has led to deep penetration into society, it has also become a breeding ground for crime, from phishing and virus spread to cyberattacks.
　In Part 1 and 2, I have introduced my experience with email and a breakdown of emails I've received. I hope you find this interesting as you compare it to your own experience.

→ Past Top Pages

　　"From Daily Life"
　　　　　　　1: Tracing family roots
　　　　　　　2: The second last car
　　　　　　　3: August 15. my memorial day
　　　　　　　4: Battlefield rations
　　　　　　　5: Begginer at the gym
　　　　　　　6: Fuji View Hotel
　　　　　　　7: Lesson in Hiragana writing by brush
　　　　　　　8: Moving from old to new smartphone
　　　　　　　9: Living alone in my second year
　　　　　　　10: Welcomed by cherry blossom
　　　　　　　11: Eden of peach blossom
　　　　　　　12: Tama River Walk
　　　　　　　13: Chichibu Pilgrimage
　　　　　　　14: Bonds with local community
　　　　　　　15: About my homepage
　　　　　　　16: Annual report of athletic gym
　　　　　　　17: Pilgrimage to Mt. Tsukuba
　　　　　　　18: Reunion of alumni and classmates
　　　　　　　19: Braking by left foot
　　　　　　　20: Battlefield rations in the sequel
　　　　　　　21: Granddaughter has come!
　　　　　　　22: Visit to Kobayashi Residence
　　　　　　　23: Wake-up exercise
　　　　　　　24: Digital photo album
　　　　　　　25: Seven tools for brushing teeth
　　　　　　　26: Ambulance
　　　　　　　27: Quick report on drive monitoring
　　　　　　　28: Hearing aid
　　　　　　　29: Jindai Botanical Park
　　　　　　　30: 2020, a historic year
　　　　　　　31: Topics of eye
　　　　　　　32: Final report on drive monitoring
　　　　　　　33: Cognitive ability test
　　　　　　　34: PCI to prevent heart infarction
　　　　　　　35: Ashikaga Flower Park
　　　　　　　36: 90 years old supported by medication
　　　　　　　37: 3 years with Subaru
　　　　　　　38: 45 years living in Seijo
　　　　　　　39: Caspian Sea yogurt
　　　　　　　40: Home Museum of Aunt Zschäbitz
　　　　　　　41: Reunion of university classmates
　　　　　　　42: Okutama spar tour
　　　　　　　43: New Year's greeting card
　　　　　　　44: Implant
　　　　　　　45: Fuchu Forest Park
　　　　　　　46: Grave closing
　　　　　　　47: Walking group of local community
　　　　　　　48: How-to books for the elderly
　　　　　　　49: Home altar
　　　　　　　50: Such a life
　　　　　　　51: Knee of the elderly
　　　　　　　52: Metropolitan Kinuta Park
　　　　　　　53: Shirakaba Art Museum of Kiyoharu
　　　　　　　54: Haiku; Metasequoia
　　　　　　　55: Three years with COVID-19
　　　　　　　56: Battlefield rations in the 6th year
　　　　　　　57: Hearing impairment
　　　　　　　58: Shinjuku Station
　　　　　　　59: Haiku with photograph
　　　　　　　60: Moving to 5G smartphone
　　　　　　　61: History of private cars
　　　　　　　62: Setagaya Art Museum
　　　　　　　63: FreeCell
　　　　　　　64: Turbo
　　　　　　　65: Hinata Temple of Yakushi
　　　　　　　66: Moving of home computer
　　　　　　　67: Amakusa tour
　　　　　　　68: Hand craft as a hobby
　　　　　　　69: Kitami Community Square
　　　　　　　70: Photo-Haiku 2
　　　　　　　71: Support scam abusing Trojan Horse
　　　　　　　72: Bedside gym
　　　　　　　73: Metropolitan Nogawa Park
　　　　　　　74: Family funeral
　　　　　　　75: Sudoku (Number Place)
　　　　　　　76: Photo-Haiku 3
　　　　　　　77: Ohyama Afri Shrine
　　　　　　　78: Kunisaki Peninsula tour
　　　　　　　79: The old school system is far away
　　　　　　　80: Cooking group of local community
　　　　　　　81: Motor fan group of local community
　　　　　　　82: Directories disappear!
　　　　　　　83: Tunnel ventilation
　　　　　　　84: Hearing aid renewal
　　　　　　　85: Photo-Haiku 4
　　　　　　　86: Digital records of life
　　　　　　　87: 80 years after the ceasefire
　　　　　　　88: Diagnosis of walking ability
　　　　　　　89: Tracing back in time
　　　　　　　90: Tour around castles and potteries
　　　　　　　91: Asset management
　　　　　　　92: Email - Part 1

　　"Memorable Scenes"
　　　　　　Series 1: Parade with Doctor hat on the head
　　　　　　Series 2: Calligraphy in a frame
　　　　　　　 Series 3: A young man from the Orient
　　　　　　　 Series 4: Sumo-stamping
　　　　　　　 Series 5: Waiting room of Shanghai Station
　　　　　　　 Series 6: Let's Walk Festival
　　　　　　　 Series 7: Last long-distance drive
　　　　　　Series 8: My Car No. 3
　　　　　　Series 9: Ski camp
　　　　　　Series 10: Safari experience
　　　　　　　Series 11: First encounter with dogwood
　　　　　　　Series 12: Mt. Fuji

　　"Treasure Box of Words"
　　　　　　Series 1: Virtue brings profit
　　　　　　Series 2: Wait for a ripe moment
　　　　　　Series 3: Catch the symptoms
　　　　　　Series 4: Words are selected metaphors
　　　　　　Series 5: Start with two humans
　　　　　　Series 6: Optimism is a will, pessimism a mood
　　　　　　Series 7: Atop a summit, and another becomes visible
　　　　　　Series 8: We see only what we want to see
　　　　　　　 Series 9: Chanllenge is the privilage of the young
　　　　　　　 Series 10: Today is the first day of my life

　　 Engineer Series 1: Who's engineer, juveniles' answer
　　　　　　Series 2: Corus of "We raise engineers!"
　　　　　　Series 3: From Nobel Prize to Gold Medal
　　　　　　Series 4: Professionals in three categories
　　　　　　Series 5: Various tasks in engineering
　　　　　　Series 6: Classification of EPs by IEA
　　　　　　Series 7: Science, technology and related professionals
　　　　　　Series 8: Proposal for the classification of engineers
　　　　　　Series 9: Revised proposal for the classification of engineers
　　　　　　Series 1 - 10: Whole Series including summary and remarks

　　 Cartoon Series 1: Mechanism of viscosity
　　　　　 Series 2: Mechanism of loss generation
　　　　　 Series 3: Commuter packer and enthalpy
　　　　　 Series 4: Skinny grasshopper and fat pupa
　　　　　 Series 5: From hand-drawn picture to ready-made clip art
　　　　　 Series 6: Why do you learn? - 1
　　　　　 Series 7: Why do you learn? - 2
　　　　　 Series 8: Two Sciences
　　　　　 Series 9: Scientist and Engineer
　　　　　 Series 10: Science and Non-science
　　　　　　 Series 11: Structure of human relations
　　　　　　Series 12: Oriental subconsciousness

　　 Nostalgia Series 1: The first own car
　　　　　 Series 2: The first driver's license
　　　　　 Series 3: Comparison of German and Japanese Diploma
　　　　　 Series 4: The first air travel
　　　　　 Series 5: Tachometer used 60 years ago
　　　　　 Series 6: The three sacred calculators
　　　　　 Series 7: The first home computer
　　　　　 Series 8: Sentimental journey to Nordkapp
　　　　　 Series 9: Change of photograph
　　　　　 Series 10: Story of passport

　　 The others

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Let's find facts! 　Final version revised in August, 2016.

Japanese universities found in statistics

Topics 1: Age distribution of new entrants
Topics 2: Comparison of completion rate
Topics 3: Timing when students start seeking a job
Topics 4: Ranking by IMD World Competitiveness Yearbook

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Brief Self Introduction

Born in 1931 in Tokyo, male, married, two sons and five grandchildren. 175-2 cm tall (due to ageing) , weight 66+ε kg (target; ε=zero, reality; ε=1), gray hair with 20 % darkness. Lost wife in 2017 and live alone.
Studied mechanical engineering. Five years industrial experience as a gas turbine design engineer, including two years doctoral research at Technische Hochschule Braunschweig, Germany.
1959-1992: 33 years education and research at Mechanical Engineering Department of the University of Tokyo, specified in fluids engineering with emphasis on the application to turbomachinery. Emeritus Professor of the University after retirement.
1992-2003: 11 years education as Professor of Mechanical Engineering of Kogakuin University, a private engineering college established in 1887 with some 6000 undergraduate and 700 graduate students. Nine years of that period were spent for administration of the University as the President from 1994 through 2003. Emeritus Professor of the University after the second retirement.
2003 to 2011: Chair, Board of Directors, Incorporated Educational Institution "Kogakuin University". The Institution manages the University along with two attached schools, a junior high and a high school.
Advisor to Japan Federation of Engineering Societies (JFES) and Japan Accreditation Board for Engineering Education (JABEE).
Member of the Engineering Academy of Japan (EAJ).

Mail address: PGA02322@nifty.com
Place of residence: Tokyo, Japan

Major Past Activities

As the President and Chiar of "Kogakuin University": The origin of Kogakuin University was founded in 1887 as a private two-year college of technology. Responding to the increasing needs for qualified engineers, it was converted in 1949 to a modern four-year university specialized in engineering education. Tokyo Urban Tech, the sub-name of the University, comes from the facts that the main campus is located at the heart of the Metropolis, and many of our researches deal with engineering problems arising from urbanization. More than 90 thousand graduates from our schools spread out to every sector of industries and are supporting the basis of modern industrial society. The total enrollment of our university and attached schools is around 8000. The Board of Directors is responsible for the management and financing of the Educational Institution.
To Establish Engineering Profession in Japan: Modern society is filled with human-made products that are planned, designed, manufactured and operated by engineers. Engineers are responsible for the safety and reliability of their products, similar to medical doctors who are responsible for the health of people. Engineering profession of today must be quality-assured with globally compatible standards. In accordance with this new requirement, our Professional Engineers Act was revised in 2000 by the proposals compiled by the Council of Professional Engineers of Science and Technology Agency, and went into effect since April, 2001. Engineering education is the basis of the profession and the quality must be assured by an accreditation process. In November 1999, Japan Accreditation Board for Engineering Education (JABEE) was founded as the accreditation agency representing Japan. I am one of the founding members and have been supporting the development and management of JABEE since its foundation. JABEE became the provisional member of the Washington Accord in 2001 and became the 9th signatory in 2005.
Other past activities: Director, Hatakeyama Culture Foundation; Councilor, Kurata Memorial Hitachi Science and Technology Foundation, etc

Membership of Academic/Professional Societies

Japan Society of Mechanical Engineers (President 92-93); Turbomachinery Society of Japan (President 90-92); Multi-Phase Flow Society of Japan (President 91-93); Japan Society of Aero- and Astronautics; Gas Turbine Society of Japan; Visualization Society of Japan; Japan Society of Hydro- and Pneumatic Engineering; Japan Society of Fluid Mechanics; Chinese Mechanical Engineering Society (Honorary Member 91- ).
Engineering Academy of Japan (Member since 1986)
Japan Federation of Engineering Societies (President 99-03, advisor, fellow)
Japan Society for Engineering Education (Vice-President 98-04)
Japan Accreditation Board for Engineering Education (Vice-President 99-05, President 05-09, advisor)
Science Council of Japan (Council Member 91-00, Director of Engineering Division 97-00, Member 06-11)

Curriculum Vitae

Graduated from the Department of Mechanical Engineering, School of Engineering, University of Tokyo in March 1954.
April 1954 - June 1959: Design engineer of gas turbine and industrial compressors at Ishikawajima Heavy Industries, Ltd.
October 1956 - September 1958: Research student (on DAAD Stipend) with supervision of Prof. H. Schlichting at Technische Hochschule Braunschweig, Germany. Obtained Dr.-Ingenieur Degree in August 1958 by the thesis work on tandem compressor cascades.
July 1959 - March 1992: Faculty staff at the Department of Mechanical Engineering, University of Tokyo, specialized in fluids engineering and fluid machinery. Lecturer (1959), Associate Professor (1960) and Professor (1976-1992). Professor Emeritus (1992-).
April 1992- March 2003: Professor of Mechanical Engineering at Kogakuin University. April 1994 - March 2003: President of the University. Professor Emeritus (2003-).
April 2003 - March 2011: Chair, Board of Directors, Incorporated Educational Institution "Kogakuin University".
Awards: Paper Award of Japan Society of Mechanical Engineers (1969, 1980, 1984 and 1993); Paper Award of Turbomachinery Society of Japan (1986); National Medal of Honors with Blue Ribbon (1992, contribution to industrial standardization); National Medal of Honors with Purple Ribbon (1997, contribution for the progress of fluids engineering); Minister's Award of MITI (1987, contribution to industrial standardization); Minister's Award of Science and Technology Agency (1995, contribution to the safety of nuclear power generation); Order of the Sacred Treasure, Gold Rays with Neck Ribbon (2011, national conferment); Distinguished Engineer Award (2015, Asian Fluid Machinery Committee); Distinguished Achievement Award (2018, Turbomachinery Sociedty of Japan).
Main research theme: Steady and unsteady cascade flow; unsteady performance of turbomachinery; unsteady fluid forces on whirling impellers of turbomachinery; unsteady loss characteristics of piping elements such as branch, diffuser and step; two-phase flow in turbopumps; instability of two- phase flow pumping system; two-phase flow in two-dimensional cascades, analysis and experiment; diffusion in turbulent wall jet; longitudinal diffusion in vehicle tunnels; ventilation, safety and environmental problems of vehicle tunnels; numerical simulation of vehicle fire in tunnels; environmental fluid mechanics.

Recent Publications

The center of gravity of recent publications has been shifting from those with the topics in fluids engineering to those in engineering education. Please refer to Publications List of the recent papers written in English.