Kenichiro UMEZUProfessor

■Researcher basic information

Organization

  • College of Education Training Course for School Teachers Program for Subject Education / Major in Mathematics Education
  • Graduate School of Education(Course for Professional degree ) Division of Professional Teacher Education Professional Course in School Subjects
  • Faculty of Basic Natural Science Domain of Mathematics and Informatic

Research Areas

  • Natural sciences, Mathematical analysis, Nonlinear partial differential equations

Research Keyword

  • nonlinear elliptic boundary value problem, eigenvalue problem, positive solution, bifurcation analysis, variational approach, degree theory, sub- and supersolutions, population dynamics.

Degree

  • 1990年03月 修士(理学)(筑波大学)
  • 1993年03月 博士(数学)(筑波大学)

Educational Background

  • Apr. 1988 - Mar. 1993, University of Tsukuba, Graduate School, Division of Mathematics
  • Apr. 1984 - Mar. 1988, University of Tsukuba, First Cluster of College, College of Natural Sciences

Career

  • Apr. 2024 - Present, Department of Mathematics, Ibaraki University, Professor
  • Apr. 2012 - Mar. 2024, Faculty of Eduation, Ibaraki University, Professor
  • Apr. 2008 - Mar. 2012, Faculty of Education, Ibaraki University, Associate Professor
  • Apr. 2007 - Mar. 2008, Maebashi Institute of Technology, Associate Professor
  • Apr. 2001 - Mar. 2007, Maebashi Institute of Technology, Associate Professor
  • Apr. 1997 - Mar. 2001, Maebashi Institute of Technology, Lecturer
  • Mar. 1997 - Mar. 1997, Institute of Mathematics, University of Tsukuba, Research Associate
  • Jun. 1993 - Feb. 1997, Institute of Mathematics, University of Tsukuba, Researcher

■Research activity information

Paper

MISC

Lectures, oral presentations, etc.

  • Positive solutions of a diffusive logistic equation with a non Lipschitz boundary condition arising in coastal fishery harvesting               
    Kenichiro Umezu
    Division of Functional Equations, The 2020 Annual Meeting of MSJ, 18 Mar. 2025, MSJ
    20250318, 20250321
  • Positive solutions for logistic type elliptic equation with a non Lipschitz boundary condition arising in coastal fishery harvesting               
    Kenichiro Umezu
    Equadiff2024 in Karlstad, 13 Jun. 2024
    20240610, 20240614
  • Positive solutions for some sublinear Robin problem with an indefinite weight               
    Kenichiro Umezu
    The Friday Seminar of Ibaraki University, 07 Jul. 2023, [Invited]
    20230707, 20230707
  • An exact multiplicity result for some sublinear Robin problem with an indefinite weight               
    Kenichiro Umezu
    The 13th AIMS Conference on Dynamical Systems, Differential Equations and Applications in Wilmington NC, 01 Jun. 2023, AIMS(American Institute of Mathematical Sciences), [Invited]
    20230531, 20230604
  • Logistic elliptic equations with the nonlinear boundary condition arising in coast fishery harvesting               
    Kenichiro Umezu
    The Applied Mathematical Analysis Seminar of Tohoku University, 09 Jun. 2022, 東北大学大学院理学研究科数学教室, [Invited]
  • Uniqueness of a positive solution for the Laplace equation with indefinite superlinear boundary conditions: near a critical case               
    Kenichiro Umezu
    The South Osaka Applied Mathematics Seminar, 11 Dec. 2021, 大阪市立大学理学研究科, [Invited]
  • Global exact multiplicity of positive solutions for an indenite sublinear Robin problem               
    Kenichiro Umezu
    Division of Functional Equations, The 2020 Annual Meeting of MSJ, 16 Mar. 2020, 日本数学会
  • Existence of a loop of positive solutions for concave-convex problems with indefinite weights               
    Kenichiro Umezu
    Equadiff 2019 in Leiden, 11 Jul. 2019
  • Exact multiplicity of positive solutions for an indefinite concave Robin bvp               
    Kenichiro Umezu
    Division of Functional Equations, The 2019 Annual Meeting of MSJ, 17 Mar. 2019, 日本数学会
  • Positivity of bifurcating nontrivial nonnegative solutions of indefinite concave problems               
    Kenichiro Umezu
    The 12th AIMS Conference on Dynamical Systems, Differential Equations and Applications in Taipei, 06 Jul. 2018, American Institute of Mathematical Sciences, [Invited]
  • Loop components of nontrivial nonnegative solutions for indefinite concave-convex problems               
    Kenichiro Umezu
    Division of Functional Equations, The 2018 Annual Meeting of MSJ, 18 Mar. 2018, 日本数学会
  • Subcontinua of loop for positive solutions to concave-convex elliptic boundary value problems               
    Kenichiro Umezu
    Variation Problem Seminar of Tokyo Metropolitan University, 14 Dec. 2017, 首都大学東京理工学研究科数理情報科学専攻, [Invited]
  • Positivity for nontrivial nonnegative solutions of an indefinite sublinear problem               
    Kenichiro Umezu
    Division of Functional Equations, The 2017 Annual Meeting of MSJ, 24 Mar. 2017, 日本数学会
  • On the existence of a loop component of nontrivial non-negative solutions for some concave-convex problem               
    Kenichiro Umezu
    Workshop on reaction diffusion equations and numerical analysis (Kyoto Sangyo University), 08 Oct. 2016, [Invited]
  • A loop type component of positive solutions of an indefinite concave-convex problem with the Neumann boundary condition               
    Kenichiro Umezu
    The 11th AIMS Conference on Dynamical Systems, Differential Equations and Applications in Orlando, 04 Jul. 2016, American Institute of Mathematical Sciences (AIMS), [Invited]
  • An indefinite superlinear elliptic equation with a nonlinear boundary condition of sublinear type               
    Kenichiro Umezu
    RIMS Workshop `Shapes and other properties of solutions of PDEs' (RIMS, Kyoto University), 13 Nov. 2015, [Invited]
  • Bifurcation analysis for a logistic elliptic equation having nonlinear boundary conditions with sign-definite weights               
    Kenichiro Umezu
    Seminar of Department of Mathematics, Universidad de Santiago de Chile, 01 Sep. 2015, Department of Mathematics, Universidad de Santiago de Chile, [Invited]
  • Role of indefinite weights for the structure of the solution set of concave-convex mixed boundary value problems               
    Kenichiro Umezu
    Division of Functional Equations, The 2015 Annual Meeting of MSJ, 21 Mar. 2015, 日本数学会
  • The effect of a nonlinear boundary condition with an indefinite weight on the positive solution set of the logistic elliptic equation               
    Kenichiro Umezu
    The 10th AIMS Conference on Dynamical Systems, Differential Equations and Applications in Madrid, 08 Jul. 2014, AIMS(American Institute of Mathematical Sciences), [Invited]
  • On S-shaped and CS-shaped bifurcation diagrams in population dynamics               
    Kenichiro Umezu
    Division of Functional Equations, The 2014 Annual Meeting of MSJ, 17 Mar. 2014, 日本数学会
  • On the effect of spatial heterogeneity in logistic type elliptic equations with nonlinear boundary conditions               
    Kenichiro Umezu
    The 9th AIMS Conference on Dynamical Systems, Differential Equations and Applications in Orlando, 04 Jul. 2012, American Institute of Mathematical Sciences, [Invited]
  • Global structure of bifurcation for positive solutions to nonlinear elliptic boundary value problems of logistic type               
    Kenichiro Umezu
    Variation Problem Seminar of Tokyo Metropolitan University, 09 Mar. 2012, 首都大学東京理工学研究科数理情報科学専攻, [Invited]
  • Global bifurcation of positive solutions for some elliptic problems with nonlinear boundary conditions               
    Kenichiro Umezu
    Toya Analysis Seminar, 28 Sep. 2010, [Invited]
  • Global bifurcation analysis of indefinite nonlinear boundary value problems with nonlinear boundary conditions               
    Kenichiro Umezu
    The 8th AIMS Conference on Dynamical Systems, Differential Equations and Applications in Dresden, 27 May 2010, American Institute of Mathematical Sciences, [Invited]
  • Global bifurcation for indefinite weighted elliptic problems with nonlinear boundary conditions               
    Kenichiro Umezu
    Division of Functional Equations, The 2010 Annual Meeting of MSJ, 25 Mar. 2010, 日本数学会
  • A super and subsolution method for sublinear problems with low regularity coefficients               
    Kenichiro Umezu
    Division of Functional Equations, The 2008 Annual Meeting of MSJ in Autumn, 25 Sep. 2008, 日本数学会
  • Blowing-up properties of the positive principal eigenvalue for indefinite Robin-type boundary conditions               
    Kenichiro Umezu
    The Second China-Japan Colloquium of Mathematical Biology in Okayama, 06 Aug. 2008
  • Nehari manifolds, fibering maps and semilinear elliptic boundary value problems               
    Kenichiro Umezu
    Mathematical Science Seminar, 10 Sep. 2007
  • Multiplicity of positive solutions to nonlinear elliptic boundary value problems arising in population dynamics               
    Kenichiro Umezu
    Workshop "Direct, Inverse And Control Problems For PDE's" in Rome, 27 Jun. 2007
  • Principal eigenvalues of Neumann and Robin type eigenvalue problems with indefinite weights               
    Kenichiro Umezu
    The 4th International Conference on Mathematical Biology in Wuyishan, 01 Jun. 2007, [Invited]
  • Principal eigenvalues and population dynamics               
    Kenichiro Umezu
    Division of Functional Equations, The 2007 Annual Meeting of MSJ, 28 Mar. 2007, 日本数学会
  • Blowing-up principal eigenvalues of Neumann eigenvalue problems with indefinite weights               
    Kenichiro Umezu
    Analysis Seminar (Institute of Math., University of Tsukuba), 20 Dec. 2006, 筑波大学数学系
  • Principal eigenvalues for Neumann boundary conditions               
    Kenichiro Umezu
    Applied Analysis Seminar (Waseda University), 02 Dec. 2006, 早稲田大学理工学部数学科
  • Principal eigenvalues for Neumann boundary conditions               
    Kenichiro Umezu
    Mathematical Science Seminar, 10 Sep. 2006
  • Blowing-up behavior of principal eigenvalues for Neumann boundary conditions               
    Kenichiro Umezu
    The first China-Japan Colloquium of Mathematical Biology (CJCMB) in Chongqing, 25 Apr. 2006
  • Principal eigenvalues for Robin boundary conditions               
    Kenichiro Umezu
    Division of Functional Equations, The 2006 Annual Meeting of MSJ, 27 Mar. 2006, 日本数学会
  • Elliptic eigenvalue problems with indefinite Robin boundary conditions               
    Kenichiro Umezu
    ISAAC05, the 5th Congress in Catania, 29 Jul. 2005, [Invited]
  • An estimate for turning points in sublinear elliptic boundary value problems               
    Kenichiro Umezu
    Division of Functional Equations, The 2005 Annual Meeting of MSJ, 28 Mar. 2005, 日本数学会
  • Stationary solutions of diffusive logistic equations with large diffusion and nonlinear boundary conditions               
    Kenichiro Umezu
    Mathematical Science Seminar, 18 Jul. 2004
  • Existence and nonexistence of positive solutions for a semilinear elliptic problem arising in population dynamics               
    Kenichiro Umezu
    Nonlinear Elliptic and Parabolic Problems: A Special Tribute to the Work of Herbert Amann in Zurich, 30 Jun. 2004
  • Existence and limiting behavior of positive solutions for diffusive logistic equations with nonlinear flux on the boundary               
    Kenichiro Umezu
    Division of Functional Equations, The 2003 Annual Meeting of MSJ in Autumn, 27 Sep. 2003, 日本数学会
  • Multiplicity and behavior of positive solutions to nonlinear elliptic equations arising in population dynamics               
    Kenichiro Umezu
    Colloquium of Institute of Mathematics, University of Tsukuba, 04 Sep. 2003, 筑波大学数学系
  • On diffusive logistic equations having nonlinear boundary conditions               
    Kenichiro Umezu
    ISAAC03, the 4th Congress in Toronto, Aug. 2003, ISAAC, [Invited]
  • Multiplicity of positive solutions to a nonlinear elliptic boundary value problem arising in population dynamics               
    Kenichiro Umezu
    Variation Problem Seminar of Tokyo Metropolitan University, Feb. 2003, 東京都立大学理学部数学教室, [Invited]
  • Bifurcation analysis of a semilinear elliptic problem arising in population dynamics and having nonlinear boundary conditions               
    Kenichiro Umezu
    Mathematical Analysis for Self-Interacting Particle System, Nov. 2002, 大阪大学基礎工学部, [Invited]
  • Bifurcation problem for a semilinear elliptic equation arising in population dynamics, having nonlinear boundary conditions               
    Kenichiro Umezu
    International Conference on Nonlinear Partial Differential Equations Theory and Approximation in Hong Kong, Aug. 2002
  • Local and global bifurcation analysis on a nonlinear problem from population               
    Kenichiro Umezu
    Mathematical Science Seminar, Jun. 2002
  • Global subcontinua arising in population dynamics               
    Kenichiro Umezu
    Division of Functional Equations, The 2002 Annual Meeting of MSJ, Mar. 2002, 日本数学会
  • Bifurcation in population dynamics               
    Kenichiro Umezu
    The 4th European Conference on Elliptic and Parabolic Problems in Gaeta, Sep. 2001
  • Bifurcation analysis in diffusive logistic equations with nonlinear boundary conditions               
    Kenichiro Umezu
    ISAAC01, the 3rd Congress in Berlin, Aug. 2001, ISAAC, [Invited]
  • Bifurcation on nonlinear eigenvalue problems in population dynamics               
    Kenichiro Umezu
    Analysis Seminar (Institute of Math., University of Tsukuba), May 2001, 筑波大学数学系
  • Bifurcation in Population Genetics               
    Kenichiro Umezu
    Division of Functional Equations, The 2001 Annual Meeting of MSJ, Mar. 2001, 日本数学会
  • Bifurcation in population models               
    Kenichiro Umezu
    Biological phenomena and nonlinear differential equations (Hiroshima University), Sep. 2000
  • Diffusive logistic equations with indefinite weights and nonlinear boundary ,conditions               
    Kenichiro Umezu
    Mathematical Science Seminar, May 2000
  • Positive solutions for population model under a nonlinear boundary condition               
    Kenichiro Umezu
    Division of Functional Equations, The 2000 Annual Meeting of MSJ, Mar. 2000, 日本数学会
  • Bifurcation from infinity and uniqueness of positive solutions to semilinear elliptic equations with nonlinear boundary conditions               
    Kenichiro Umezu
    Division of Functional Equations, The 2000 Annual Meeting of MSJ, Mar. 2000, 日本数学会
  • Positive solutions for population model under a nonlinear boundary condition               
    Kenichiro Umezu
    Biological phenomena and nonlinear differential equations (Hiroshima University), Nov. 1999
  • Bifurcation and stability for diffusive logistic equations with nonlinear boundary conditions               
    Kenichiro Umezu
    International Conference on Nonlinear Partial Differential Equations 99 in Lviv, Aug. 1999
  • Elliptic boundary value problems with nonlinear boundary conditions               
    Kenichiro Umezu
    ICIAM 99, the 4th Congress in Edinburgh, Jul. 1999, ICIAM, [Invited]
  • Diffusive logistic equations with nonlinear boundary conditions               
    Kenichiro Umezu
    Mathematical Science Seminar, Jun. 1999
  • Asymptotical stability in chemical reactor theory               
    Kenichiro Umezu
    Division of Functional Equations, The 1999 Annual Meeting of MSJ, Mar. 1999, 日本数学会
  • Nonlinear elliptic boundary value problem arising in fermentation industry               
    Kenichiro Umezu
    Analysis Seminar (Institute of Math., University of Tsukuba), Jan. 1999, 筑波大学数学系
  • Positive solutions of semilinear elliptic boundary value problems               
    Kenichiro Umezu
    Division of Functional Equations, The 1998 Annual Meeting of MSJ in Autumn, Oct. 1998, 日本数学会
  • Nonlinear elliptic boundary value problem arising in fermentation industry               
    Kenichiro Umezu
    Biological phenomena and nonlinear differential equations (Hiroshima University), Sep. 1998
  • Positive solutions of semilinear elliptic boundary value problems               
    Kenichiro Umezu
    Nagano Symposium on partial differential equations, Jul. 1998
  • Stability in chemical reactor theory               
    Kenichiro Umezu
    Division of Functional Equations, The 1998 Annual Meeting of MSJ, Mar. 1998, 日本数学会
  • Semilinear elliptic boundary value problem and its application               
    Kenichiro Umezu
    Seminar on partial differential equations, Oct. 1997, 東京都立大学理学部数学教室, [Invited]
  • Semilinear elliptic boundary value problems in chemical reactor theory               
    Kenichiro Umezu
    Variational problems and related topics (RIMS, Kyoto University), Jun. 1997, RIMS, Kyoto Univ., [Invited]
  • Semilinear elliptic boundary value problems in chemical reactor theory               
    Kenichiro Umezu
    ISAAC1997, the 1st Congress in Delaware, Jun. 1997, International Society for Analysis, its Applications and Computation, [Invited]
  • Semilinear elliptic boundary value problem arising in chemical reactor theory               
    Kenichiro Umezu
    Division of Functional Equations, The 1997 Annual Meeting of MSJ, Apr. 1997, 日本数学会
  • Semilinear elliptic boundary value problem arising in chemical reactor theory               
    Kenichiro Umezu
    Applied Analysis Seminar (Waseda University), Dec. 1996, 早稲田大学理工学部数学科
  • Fourier multipliers in weighted Lp spaces               
    Kenichiro Umezu
    Real Analysis Symposium in Oita, Nov. 1996
  • Existence and uniqueness of positive solutions for semilinear elliptic boundary value problems               
    Kenichiro Umezu
    Division of Functional Equations, The 1996 Annual Meeting of MSJ, Apr. 1996, 日本数学会
  • Existence and uniqueness of positive solutions for semilinear elliptic boundary value problems               
    Kenichiro Umezu
    Seminar on differential equations, Dec. 1995, 早稲田大学理工学部数学科, [Invited]
  • Existence and uniqueness of positive solutions for semilinear elliptic boundary value problems               
    Kenichiro Umezu
    Division of Functional Equations, The 1995 Annual Meeting of MSJ in Autumn, Sep. 1995, 日本数学会
  • Positive solutions of semi linear elliptic boundary value problems               
    Kenichiro Umezu
    Kashikojima symposium on partial differential equations, Sep. 1995
  • Bifurcation for nonlinear elliptic boundary valuer problems               
    Kenichiro Umezu
    Division of Functional Equations, The 1995 Annual Meeting of MSJ, Mar. 1995, 日本数学会
  • Besov spaces with variable order               
    Kenichiro Umezu
    Function space and its application, Jan. 1994, 筑波大学数学系
  • L^p approach to mixed boudary value problems of second order               
    Kenichiro Umezu
    Division of Functional Equations, The 1993 Annual Meeting of MSJ in Autumn, Sep. 1993, 日本数学会

Affiliated academic society

  • Jan. 2001 - Present, 日本応用数理学会
  • Jun. 1993 - Present, 日本数学会

Research Themes