Koike, Ryo

写真a

Affiliation

Faculty of Science and Technology, Department of System Design Engineering ( Yagami )

Position

Associate Professor
Scopus Paper Info  
Paper Count: 62 Citation Count: 471 h-index: 13

Click to view the Scopus page. The data was downloaded from Scopus API in August 23, 2026, via http://api.elsevier.com and http://www.scopus.com .

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Career 【 Display / hide 】

  • 2016.04
    -
    2019.03

    Keio University, Faculty of Science and Engineering, Department of System Design Engineering, Research Associate (Temporary)

  • 2019.04
    -
    2024.03

    Keio University, Faculty of Science and Engineering, Department of System Design Engineering, Senior Assistant Professor

  • 2024.04
    -
    Present

    Keio University, Faculty of Science and Engineering, Department of System Design Engineering, Associate Professor

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Academic Background 【 Display / hide 】

  • 2008.04
    -
    2012.03

    Keio University, Faculty of Science and Engineering, Department of System Design Engineering

    University, Graduated

  • 2012.04
    -
    2013.09

    Keio University, The Graduate School of Science and Technology, Integrated Design Engineering

    Graduate School, Completed, Master's course

  • 2013.09
    -
    2016.03

    Keio University, The Graduate School of Science and Technology, Integrated Design Engineering

    Graduate School, Completed, Doctoral course

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Academic Degrees 【 Display / hide 】

  • 修士（工学）, Keio University, Coursework, 2013.09

  • 博士（工学）, Keio University, Coursework, 2016.03

    Realtime monitoring and stability diagnosis of cutting process by applying disturbance observer

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Research Areas 【 Display / hide 】

  • Manufacturing Technology (Mechanical Engineering, Electrical and Electronic Engineering, Chemical Engineering) / Manufacturing and production engineering (Additive Manufacturing, 3D printer, Metal AM, High gravity, femtosecond laser machining)

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Papers 【 Display / hide 】

  • Femtosecond laser-induced microstructural visualization of stainless steel surfaces

    Ueda A., Yano T., Koike R.

    Precision Engineering 102   799 - 806 2026.06

    Research paper (scientific journal), Joint Work, Last author, Corresponding author, Accepted

    　View Summary

    Femtosecond laser-induced microstructural visualization of stainless steel surfaces was investigated as a simple approach for revealing crystallographic heterogeneity in polycrystalline metals. Pocket machining experiments were performed on ferritic and austenitic stainless steels to compare their laser-induced surface responses. For ferritic stainless steel (SUS430), the resulting surface morphologies were further correlated with crystallographic orientation using electron backscatter diffraction. Under identical irradiation conditions, localized smooth and roughened regions appeared within the same machined pocket. In ferritic stainless steel (SUS430), grains oriented near the (111) plane showed an earlier transition to roughened regions, whereas other orientations remained relatively smooth. Three-dimensional surface measurements showed that the observed contrast mainly originated from differences in surface roughness rather than differences in material removal depth. The roughened regions were more consistent with chaotic laser-induced pattern (CLP)-type morphology than with wavelength-scale periodic structures. The clearest microstructural visualization was obtained at 9.35 J/cm2, indicating that an appropriate fluence window exists for this approach. These results provide a fundamental basis for a femtosecond laser-based auxiliary method for metallographic observation of stainless steel surfaces.

  • Fabrication of Functionally Graded Materials and Coating Technologies Using Directed Energy Deposition

    Koike R.

    Seimitsu Kogaku Kaishi Journal of the Japan Society for Precision Engineering 92 ( 3 ) 207 - 211 2026.03

    Research paper (scientific journal), Single Work, Lead author, Last author, Corresponding author,  ISSN  09120289

  • High-gravitational effect on process stabilization evaluation for material extrusion using polylactic acid filament

    Jiang X., Koike R.

    Scientific Reports 15 ( 1 )  2025.12

    Research paper (scientific journal), Joint Work, Last author, Accepted

    　View Summary

    Additive manufacturing (AM) has garnered significant attention because of its numerous benefits and transformative potential across industries, particularly in internet of things manufacturing systems. The application of AMs with gravitational acceleration has considerable scope for exploration. Material extrusion (MEX) is a versatile technology, to evaluate the effects of high gravitational forces on MEX, an experimental approach involving controlled gravitational acceleration up to 5G was implemented using a specialized high-gravitational material extrusion system. This system, leveraging centrifugal acceleration, facilitated a comprehensive assessment of material flow dynamics and resultant surface quality under varying gravitational conditions. The results clearly indicate that applying high gravitational acceleration, reaching up to 5G, notably improves the material extrusion quality and appearance. Gravity affects the flow of materials during the extrusion process, high gravity can help achieve better material deposition. The experimental assessments clearly demonstrate that a high gravitational field enhances the surface quality and appearance of fabricated parts.

  • In-situ heat treatment via preheating and liquid cooling during high-speed coating of gears by directed energy deposition

    Yokota M., Takemura S., Koike R., Maki T., Takaki K., Mori T., Hirono Y., Kakinuma Y.

    CIRP Journal of Manufacturing Science and Technology 61   114 - 127 2025.10

    ISSN  17555817

    　View Summary

    Automobile electrification has increased demand for higher-performance gears in drivetrains with specialized functional requirements beyond what conventional carburizing heat treatment can deliver. While carburizing is effective for mass production, it faces inherent limitations in achieving advanced material properties needed for next-generation applications. Therefore, this study proposes a high-speed coating method on rotational gear surfaces using directed energy deposition (DED). The proposed method can form the coating layer continuously and efficiently on the complex-shaped teeth of the gear, compared to the common method that forms coating along a complicated path matching the part's geometry. Furthermore, a localized heat treatment system integrating laser preheating and liquid cooling is introduced to precisely control material characteristics of the coating layer. Experimental results demonstrate that this combined heat treatment achieves a crack-free, hard coating layer on preformed gears. This method shows significant potential for producing customized, high-performance gears for specialized applications in next-generation vehicles while reducing process complexity.

  • Digital Twin in Process Planning of the Additive and Subtractive Process Chain for Laser Metal Deposition and Micro Milling of Stainless Steel

    Denkena B., Wichmann M., Malek T., Nguyen H.N., Kato M., Isshiki K., Koike R., Kakinuma Y.

    Journal of Manufacturing Science and Engineering 146 ( 7 )  2024.07

    ISSN  10871357

    　View Summary

    Additive and subtractive (Add/Sub) manufacturing processes are increasingly being combined to produce complex parts with unique geometries and properties. However, the design of such combined processes is often challenging as it requires a deep understanding of the interaction between the different processes. On the other hand, digital twin (DT) technology has become a powerful tool in recent years for optimizing manufacturing processes. This article explores the use of the digital twin technology for a holistic process planning of combined additive and subtractive processes. The article describes the integration of laser metal deposition (LMD) and micro-milling prediction models of resulting geometry (width and height), hardness, and surface roughness into the digital twin. This is then used for combined process planning to achieve different target values regarding resulting geometry and surface roughness. For the planning of this combined process chain, further criteria such as tool life, energy, and process time are considered in the optimization, showing the potential for sustainable and efficient production. Sensorless cutting force estimation is also used to detect small cutting forces, with the potential to use this as a soft sensor for roughness estimation. The measured width, height, and roughness as a result of the process parameters suggested by the optimization algorithms showed a mean absolute percentage error (MAPE) of 4, 17, and 16%, respectively.

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Papers, etc., Registered in KOARA 【 Display / hide 】

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Reviews, Commentaries, etc. 【 Display / hide 】

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Presentations 【 Display / hide 】

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Research Projects of Competitive Funds, etc. 【 Display / hide 】

  • 宇宙空間向け高機能樹脂材料、軌道上での3D積層造形技術の創出

    2026.04
    -
    2031.03

    Ministry of Education, Culture, Sports, Science and Technology, 宇宙戦略基金 (第2期 衛星等) 「空間自在利用の実現に向けた技術A-1」, Commissioned ｒesearch, Coinvestigator(s)

  • Submicron-Scale Metal 3D Fabrication via High-Gravitational PBF Using Metal Nanoparticles

    2025.04
    -
    2028.03

    基盤研究(B), Principal investigator

  • Low-density foam metal fabrication based on net-zero gravity process

    2022.04
    -
    2025.03

    MEXT,JSPS, Grant-in-Aid for Scientific Research, 基盤研究(B), Principal investigator

  • Metal 3D printing by powder bed fusion applying artificial gravity control

    2019.04
    -
    2022.03

    MEXT,JSPS, Grant-in-Aid for Scientific Research, Grant-in-Aid for Early-Career Scientists , Principal investigator

  • Development of direct deposition for porous structure based on molten-metal dynamics analysis with particle method

    2017.04
    -
    2019.03

    MEXT,JSPS, Grant-in-Aid for Scientific Research, Grant-in-Aid for Young Scientists (B), Principal investigator

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Awards 【 Display / hide 】

  • Physics of Welding Award

    2026.08, 溶接学会　溶接法研究委員会, 付加製造プロセスにおける異重力場の相似則

    Type of Award： Award from Japanese society, conference, symposium, etc.

  • KIRAMEKI AWARD

    2025.03, TANAKA Memorial Foundation, 貴金属の3D微細構造を創造する高重力場3Dプリンタの開発

    Type of Award： Award from publisher, newspaper, foundation, etc.

  • 2023年度精密工学会春季大会学術講演会 Best Presentation賞

    2023.03, 精密工学会

    Type of Award： Award from Japanese society, conference, symposium, etc.

  • 岩木トライボコーティングネットワークアワード 奨励賞

    2023.02, 未来生産システム学協会, 高重力場を援用した高機能3Dプリンタの開発

    Type of Award： International academic award (Japan or overseas)

  • Best Poster Award

    2022.11, Japan Machine Tool Builders' Association, 高重力場の援用による超高機能金属3Dプリンタの開発

    Type of Award： Award from Japanese society, conference, symposium, etc.

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Courses Taught 【 Display / hide 】

  • SYSTEM DESIGN ENGINEERING PRACTICAL RESEARCH (DOMESTIC) A

    2026

  • GRADUATE RESEARCH ON ENGINEERING AND DESIGN 2

    2026

  • SYSTEM DESIGN ENGINEERING PRACTICAL RESEARCH (DOMESTIC) D

    2026

  • SYSTEM DESIGN ENGINEERING PRACTICAL RESEARCH (INTERNATIONAL) D

    2026

  • BACHELOR'S THESIS

    2026

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